Tonight, a special edition of World News Tonight, the breaking news at this hour. President Biden announces he will not run for re-election. The historic decision of bending the race for the White House. President Biden same. Thank you, Mr. President. I love you, dad. That from Hunter Biden tonight.No matter where you are on the political spectrum, you have to keep in mind there's a family going through this after decades of public service. John Karl with us tonight. John, thank you. The Trump campaign, meanwhile, tonight, already responding to President Biden's decision to step aside here. The campaign preparing for Vice President Harris to become the Democratic nominee, already releasing a campaign ad, Attacking Harris's Record. Here again, Rachel Scott tonight.Donald Trump's response to Joe Biden's historic decision to bow out of the race tonight, Attack, Attack, Attack. Trump, who just days ago, pledged to unify the country, blasting Biden as the worst President by far in the history of our nation, adding, Whoever the left puts up now will just be more of the same. It was just over a week ago, after the attempt on Trump's life, that Trump and Biden shared what both men described as a good, respectful chat, Biden calling his rival.I spoke with him last night. I'm grateful he's doing well, and Jill and I keep him and his family in our prayers.Tonight, Trump declaring Biden was not fit to run for President, and is certainly not fit to serve. Now, some of the nation's top Republicans following Trump's lead, calling on Biden to resign from office. House Speaker Mike Johnson saying, If Joe Biden is not fit to run for President, he is not fit to serve as President. He must resign the office immediately. The Trump campaign now having to shift course though they've been preparing for weeks. Trump polling the crowd in Michigan yesterday.So who would you like to most run against, if you're us, if we want to win? Ready? Kamala Harris. Crooked Joe Biden. All right. I don't think we have to go too much further.And tonight, Trump's running mate, Senator JD Vance, bluntly saying, Joe Biden has been the worst president in my lifetime, and Kamala Harris has been right there with him every step of the way. She owns all of these failures.Rachel Scott with me here in New York at The Desk. Rachel brought you the breaking news this afternoon. We really appreciate it, Rachel. In the meantime, back to this campaign tonight. Donald Trump was hoping, many believe, that Joe Biden would be the nominee straight through November. He now has potentially someone else that he now has to target in Kamala Harris, obviously, if she officially gets the nomination. How does this look moving forward?Again, this was a curveball that the Trump campaign saw coming, but not one that they really wanted, David. They thought that they were best positioned against President Biden, given all these questions about his age, even that debate performance that he had. If Vice President Kamala Harris is the Democratic nominee, and if that debate does go forward in September, former President Donald Trump will be facing off against a former prosecutor, David.A former prosecutor who would take that debate stage, but already tonight, some questions about whether Donald Trump is willing to get on a debate stage with Kamala Harris. That's a storyline to watch as well. Rachel, thank you. Let's bring in our political director and Washington Bureau Chief, Rick Klein, with us again tonight. Rick, this was shaping up already to be a history-making convention even before the President dropped out. We should point out, as we have along the way here, that she doesn't automatically get the nomination now just because the President has endorsed her. So how does this play out?David, there is no script for what happens next. Democrats are working feverishly behind the scenes tonight to try to lock things down for Kamala Harris, to make sure that things go as smoothly as possible. At this hour, no other major Democrat has announced the candidacy or even rumblings of a candidacy. So it looks like things could be pretty smooth for her. But if that changes or if something changes in the next couple of weeks, we could be looking at a truly open convention where the 4,700 or so delegates are actually able to do whatever they want. They're the only audience that matters.And Rick, you David and I have so often talked about the polling. We know the recent polling has showed the President Biden and Donald Trump in a very tight race nationally within one or two points of each other, Donald Trump in recent days, growing that lead. But in particular, what Democrats were most concerned about was the polling in the battlegrounds. Is there any indication that Kamala Harris is in a better position in the key battlegrounds to take on Donald Trump? Yeah, David, it is still going to be a close race no matter what.But there have been some polls that suggest that Harris does a little bit better in places like a Pennsylvania, like a Michigan, some of the key battlegrounds that are so important. Nationally, the two are basically locked in a dead heat, but that's a little bit better than Biden's been doing. Our poll out today with Ipsos, David, had Kamala Harris's approval rating a little bit higher than Joe Biden, but both of them are behind Donald Trump, who is at a high point coming out of his convention. Out of that assassination attempt last week, he appears to have gotten a major bump, David.If she becomes the official nominee, a stiff challenge ahead for the vice President. Rick Klein with us tonight as well. Rick, thank you. Let's get to our Chief Global Affairs Correspondent, Martha Radetz. Martha, I'm curious what your sources are telling you tonight about President Biden's mindset here and this evolution that we learned about over the weekend.David, it was very closely held this weekend, but a senior administration official told me the President still does not believe he is mentally diminished but felt he simply did not have the energy to campaign with vigor.It is clear from the last few weeks how badly the President wanted to stay in the race, but this is a campaign that will require energy and eloquence, and President Biden has struggled with both.David. Martha Radetz in Washington tonight. Martha, I'll see you in our primetime special a short time from now. Thank you. In the meantime, when we come back on World News tonight, this Sunday, Chaos at the Miami Airport. A suspect stabs a woman at a crowded terminal, and what we're learning in a moment here. Next tonight, hear a violent knife attack at Miami's international airport, forcing the evacuation of hundreds of travelers. Authorities say a suspect stabbed a woman multiple times outside the secure area. The victim was rushed to the hospital Still in critical condition. Tonight, police say the attack was unprovoked. When we come back here on the broadcast, the fast-moving wildfire spreading across the West, the evacuations at this hour, and the latest on when we could hear from President Biden directly. When will he address the nation on his decision to drop out? To the index of other news tonight, hot, dry conditions fueling fast-moving wildfires throughout the West tonight. A blaze near Utah's state capital, forcing evacuations. The Sanhurst fire burning more than 200 acres now. And in California tonight, the Ridge fire scorching more than 2,600 acres. That's northwest of Sacramento. When we come back here, Mary Bruce is standing by.When could we hear from President Biden? He says he will address the nation on his decision to drop out of the race for President in a moment. Before we go tonight here, the Fast moving events, President Biden, of course, dropping out of the race for President. Let's get right back to Mary Bruce at the White House. Mary, this is obviously a deeply personal decision for this President after decades in public life. He said he would share more in an address to the nation. Do we have any more guidance as to when?David, President remains in isolation. No word yet on when he will come before cameras and explain to the American people this remarkable decision, a decision we know he made in just the last 24 hours, and no doubt was the most difficult decision he's ever made.David. So likely in the coming days, we will carry it live. Mary Bruce at the White House all afternoon. Mary, thank you. Our primetime special coverage of this fast moving story moments from now, 07:00 PM Eastern, right here on ABC. The entire team standing by with new reporting in a moment. Good night.Thank you for making World News Tonight with David Muir, America's most watched newscast.

same. Thank you, Mr. President. I love you, dad. That from Hunter Biden tonight.

No matter where you are on the political spectrum, you have to keep in mind there's a family going through this after decades of public service. John Karl with us tonight. John, thank you. The Trump campaign, meanwhile, tonight, already responding to President Biden's decision to step aside here. The campaign preparing for Vice President Harris to become the Democratic nominee, already releasing a campaign ad, Attacking Harris's Record. Here again, Rachel Scott tonight.

Donald Trump's response to Joe Biden's historic decision to bow out of the race tonight, Attack, Attack, Attack. Trump, who just days ago, pledged to unify the country, blasting Biden as the worst President by far in the history of our nation, adding, Whoever the left puts up now will just be more of the same. It was just over a week ago, after the attempt on Trump's life, that Trump and Biden shared what both men described as a good, respectful chat, Biden calling his rival.

I spoke with him last night. I'm grateful he's doing well, and Jill and I keep him and his family in our prayers.

Tonight, Trump declaring Biden was not fit to run for President, and is certainly not fit to serve. Now, some of the nation's top Republicans following Trump's lead, calling on Biden to resign from office. House Speaker Mike Johnson saying, If Joe Biden is not fit to run for President, he is not fit to serve as President. He must resign the office immediately. The Trump campaign now having to shift course though they've been preparing for weeks. Trump polling the crowd in Michigan yesterday.

So who would you like to most run against, if you're us, if we want to win? Ready? Kamala Harris. Crooked Joe Biden. All right. I don't think we have to go too much further.

And tonight, Trump's running mate, Senator JD Vance, bluntly saying, Joe Biden has been the worst president in my lifetime, and Kamala Harris has been right there with him every step of the way. She owns all of these failures.

Rachel Scott with me here in New York at The Desk. Rachel brought you the breaking news this afternoon. We really appreciate it, Rachel. In the meantime, back to this campaign tonight. Donald Trump was hoping, many believe, that Joe Biden would be the nominee straight through November. He now has potentially someone else that he now has to target in Kamala Harris, obviously, if she officially gets the nomination. How does this look moving forward?

Again, this was a curveball that the Trump campaign saw coming, but not one that they really wanted, David. They thought that they were best positioned against President Biden, given all these questions about his age, even that debate performance that he had. If Vice President Kamala Harris is the Democratic nominee, and if that debate does go forward in September, former President Donald Trump will be facing off against a former prosecutor, David.

A former prosecutor who would take that debate stage, but already tonight, some questions about whether Donald Trump is willing to get on a debate stage with Kamala Harris. That's a storyline to watch as well. Rachel, thank you. Let's bring in our political director and Washington Bureau Chief, Rick Klein, with us again tonight. Rick, this was shaping up already to be a history-making convention even before the President dropped out. We should point out, as we have along the way here, that she doesn't automatically get the nomination now just because the President has endorsed her. So how does this play out?

David, there is no script for what happens next. Democrats are working feverishly behind the scenes tonight to try to lock things down for Kamala Harris, to make sure that things go as smoothly as possible. At this hour, no other major Democrat has announced the candidacy or even rumblings of a candidacy. So it looks like things could be pretty smooth for her. But if that changes or if something changes in the next couple of weeks, we could be looking at a truly open convention where the 4,700 or so delegates are actually able to do whatever they want. They're the only audience that matters.

And Rick, you David and I have so often talked about the polling. We know the recent polling has showed the President Biden and Donald Trump in a very tight race nationally within one or two points of each other, Donald Trump in recent days, growing that lead. But in particular, what Democrats were most concerned about was the polling in the battlegrounds. Is there any indication that Kamala Harris is in a better position in the key battlegrounds to take on Donald Trump? Yeah, David, it is still going to be a close race no matter what.

But there have been some polls that suggest that Harris does a little bit better in places like a Pennsylvania, like a Michigan, some of the key battlegrounds that are so important. Nationally, the two are basically locked in a dead heat, but that's a little bit better than Biden's been doing. Our poll out today with Ipsos, David, had Kamala Harris's approval rating a little bit higher than Joe Biden, but both of them are behind Donald Trump, who is at a high point coming out of his convention. Out of that assassination attempt last week, he appears to have gotten a major bump, David.

If she becomes the official nominee, a stiff challenge ahead for the vice President. Rick Klein with us tonight as well. Rick, thank you. Let's get to our Chief Global Affairs Correspondent, Martha Radetz. Martha, I'm curious what your sources are telling you tonight about President Biden's mindset here and this evolution that we learned about over the weekend.

David, it was very closely held this weekend, but a senior administration official told me the President still does not believe he is mentally diminished but felt he simply did not have the energy to campaign with vigor.

It is clear from the last few weeks how badly the President wanted to stay in the race, but this is a campaign that will require energy and eloquence, and President Biden has struggled with both.

David. Martha Radetz in Washington tonight. Martha, I'll see you in our primetime special a short time from now. Thank you. In the meantime, when we come back on World News tonight, this Sunday, Chaos at the Miami Airport. A suspect stabs a woman at a crowded terminal, and what we're learning in a moment here. Next tonight, hear a violent knife attack at Miami's international airport, forcing the evacuation of hundreds of travelers. Authorities say a suspect stabbed a woman multiple times outside the secure area. The victim was rushed to the hospital Still in critical condition. Tonight, police say the attack was unprovoked. When we come back here on the broadcast, the fast-moving wildfire spreading across the West, the evacuations at this hour, and the latest on when we could hear from President Biden directly. When will he address the nation on his decision to drop out? To the index of other news tonight, hot, dry conditions fueling fast-moving wildfires throughout the West tonight. A blaze near Utah's state capital, forcing evacuations. The Sanhurst fire burning more than 200 acres now. And in California tonight, the Ridge fire scorching more than 2,600 acres. That's northwest of Sacramento. When we come back here, Mary Bruce is standing by.

When could we hear from President Biden? He says he will address the nation on his decision to drop out of the race for President in a moment. Before we go tonight here, the Fast moving events, President Biden, of course, dropping out of the race for President. Let's get right back to Mary Bruce at the White House. Mary, this is obviously a deeply personal decision for this President after decades in public life. He said he would share more in an address to the nation. Do we have any more guidance as to when?

David, President remains in isolation. No word yet on when he will come before cameras and explain to the American people this remarkable decision, a decision we know he made in just the last 24 hours, and no doubt was the most difficult decision he's ever made.

David. So likely in the coming days, we will carry it live. Mary Bruce at the White House all afternoon. Mary, thank you. Our primetime special coverage of this fast moving story moments from now, 07:00 PM Eastern, right here on ABC. The entire team standing by with new reporting in a moment. Good night.

Thank you for making World News Tonight with David Muir, America's most watched newscast.