AMNA NAWAZ: Welcome to the "News Hour."

We are here at the Republican National Convention in Milwaukee, where Ohio Senator J.D.

Vance has been tapped as the vice presidential nominee just days after a failed assassination attempt on Donald Trump and as Republicans are cheering the sudden dismissal of the classified documents case against the former president.

GEOFF BENNETT: Quite a busy day in the 2024 presidential campaign.

Our Lisa Desjardins is here with us in the middle of it all from the convention floor.

LISA DESJARDINS: Just two days after the attempt on his life, former President Donald Trump in Milwaukee, Wisconsin, for the start of the Republican National Convention,defiant and lifted by good news from his legal battles.

A federal judge in Florida dismissed Trump's classified documents case, saying that special counsel Jack Smith was illegally appointed by the Justice Department.

ERIC TRUMP, Executive Vice President, Trump Organization: For the greatest president that's ever lived, and that's Donald J. Trump.

LISA DESJARDINS: The decision can be appealed, but it handed Trump a win the same day as he formally became the party's presidential nominee and officially began his bid to return to office.

And he wasn't alone.

Alongside him at the top of the ticket, his much-anticipated choice for vice president, Ohio Senator J.D.

Vance.

Formerly a critic of Trump's, Vance once referred to Trump as America's Hitler back in 2016.

Now he's one of Trump's most vocal defenders, taking to social media after former President Trump was nearly killed and pointing a finger of blame at the Biden campaign, just one way that the shooting is hanging over the RNC, which began today as scheduled.

But for the delegates, there was enthusiasm about the party and their beliefs coming together.

SAM SOMOGYE, Harris County Republican Party: I feel great.

I think the Republican Party has never been as unified as we are in this moment.

CAROL CASSADY, Alternate Delegate, Texas: We're here and we're standing up in the name of Jesus for God, family, country.

LISA DESJARDINS: The day one agenda, make America wealthy again with a focus on the economy, but the overarching message, striving for unity in the party and the country.

Trump telling reporters who traveled with him aboard his plane to Milwaukee -- quote -- "I'm supposed to be dead.

I'm not supposed to be here."

He said he's changing the tone of his convention speech, tossing aside his initial draft.

PROTESTER: We have to defeat the Republicans!

LISA DESJARDINS: But there was vocal disagreement in Milwaukee today from protesters who gathered outside the security zone, many pro-Palestinian, but many focused on Trump.

JODI DELFOSSE, Protester: The direction that the Republicans are taking this country is very dangerous.

LISA DESJARDINS: Here too, the assassination attempt hovered.

MICHAEL TROKAN, Protester: I'm concerned it may change the direction of the election and make people more sympathetic to it, but doesn't change his policies at all.

LEONARD SOBCZAK, Protester: I think it could work against him, because what happened to him is everything that he's been espousing, violent overthrow.

LISA DESJARDINS: But blocks away, for delegates and attendees, prominently, a sense of gratitude.

MICHAEL MURPHY, Illinois Resident: I think we lucked out, but everybody's on eggshells here.

DONALD TRUMP, Former President of the United States (R) and Current U.S. Presidential Candidate: Take a look at what happened.

(GUNSHOTS) LISA DESJARDINS: This as the investigation continues.

FBI officials who are leading the investigation have yet to determine the motive of the shooter, 20-year-old Thomas Matthew Crooks, a registered Republican who made a $15 donation to a progressive organization in 2021, according to the Federal Election Commission.

And the Secret Service facing urgent questions over how they handled the shooting, including how the shooter could get so close, fewer than 500 feet from Trump's podium, and how the suspected shooter was confronted by an officer on the roof before that same officer had to pull back.

In Milwaukee, no plans for more changes to the already heavy security posture for the RNC, which is classified as a national special security event.

AUDREY GIBSON-CICCHINO, RNC Coordinator, Secret Service: We are confident in these security plans that are in place for this event, and we're ready to go.

It's been an 18-month process.

JOE BIDEN, President of the United States: My fellow Americans... LISA DESJARDINS: But President Biden is calling for many Americans to change their tone.

He spoke in the Oval Office last night.

JOE BIDEN: There's no place in America for this kind of violence, for any violence, ever, period, no exceptions.

We can't allow this violence to be normalized.

The political rhetoric in this country has gotten very heated.

It's time to cool it down.

LISA DESJARDINS: The president had paused his own campaign schedule in wake of the shooting, canceling an appearance today in Texas, but he will resume in Nevada, where he travels tonight.

Meanwhile, I'm sure somewhere tonight someone is printing out signs that say Trump/Vance, but, tonight, Amna and Geoff, delegates had to do it on their own, handwriting the name Vance in, as they just learned like you and I in the last couple of hours that will be their vice presidential nominee.

GEOFF BENNETT: Lisa, what is the Trump campaign telling you about why Mr. Trump ultimately settled on Senator Vance as his vice presidential pick?

LISA DESJARDINS: Multiple reasons.

Number one, it is about his experience and his actual biography speaking to the working class of America.

Number two, they like his military experience.

He served in the Marine Corps.

He was a correspondent in Iraq.

Number three, they also like that he is someone who is from the Rust Belt.

And in his announcement today, President -- former President Trump mentioned several states, Pennsylvania, Michigan, Minnesota, Wisconsin.

These are states that clearly could be decisive in this election.

One last thing, he's a new generation.

He's not yet 40 years old.

He will be the youngest nominee for any presidential ticket this century.

And that's something that the Trump campaign is going to push forward.

Now, they know he also has some drawbacks.

He has been critical of former President Trump in the past.

I asked the campaign about that.

They said they're going to try and message that as someone who has changed his mind.

I guarantee you Democrats will go the other way and say this is someone who saw Trump as dangerous and changed his mind because of political opportunity.

AMNA NAWAZ: Lisa, meanwhile, the man at the top of the ticket, former President Donald Trump, is expected to appear here later tonight.

You have been talking with his campaign.

What should we expect in that appearance?

LISA DESJARDINS: They are feeling good.

The former president wrote today that he has rewritten his campaign speech, we expect, on Thursday night and that he's trying to have more of a tone of unity.

That's part of the J.D.

Vance story too.

We have talked on this program about how Vance came out against Biden and the Democrats in terms of what happened on -- in the assassination attempt.

They expect some, campaign sources, Vance to be the bulldog.

It's a traditional role for the vice presidential ticket, allowing Trump to perhaps be more of a unifier here on the floor.

Now, it remains to be seen what role the Trump family will have.

There are many who are confident now, more confident than they were that Trump will win this election.

But one of them is not Donald Trump Jr.

I was in a gaggle with him just a few feet away from where I'm standing now.

And he said they're not taking any vote for granted.

They think this could be close right up to November.

GEOFF BENNETT: Well, what about the level of confidence among the delegates with whom you have been speaking?

How do they feel about Mr. Trump's standing in this race?

LISA DESJARDINS: Yes, that's the thing about J.D.

Vance.

It wasn't electric for him, to be honest.

People were very happy about it.

But this crowd is waiting for Donald Trump.

And I think right now there's sort of an air of digesting the assassination attempt still to see what that means.

And there's a question of, is this a divided or united party still?

I want to show the picture of someone I met from Arkansas.

This delegate had on the front of his hat, this alternate delegate, the Trump bumper sticker.

And then on the back of his hat, it said Nikki Haley.

And I asked him: "Well, how are you feeling about that?

You were a Haley voter.

You wanted her."

He said: "I sure did.

I thought she was going to be better than Donald Trump, but now I am all the way behind Donald Trump."

So there is some unity here.

One place there's not, Mitch McConnell.

The Republican leader of the Senate, was booed on this floor when he announced Kentucky's delegation.

So that is still a sign of the real fractures in this party.

AMNA NAWAZ: Lisa, meanwhile, you covered the Republican National Convention back in 2016 as well.

How does this one compare to that one?

LISA DESJARDINS: I will say it actually, strangely, feels a little bit more reserved early on.

I think they are waiting.

I think the assassination attempt has given people pause about the country.

And it feels a little bit more serious when I talk to delegates.

Of course, this will change over the course of the week.

This is a place where the country unites.

It's all people of one party, but you see miners' hats from West Virginia.

You see Texans wearing cowboy hats.

This is something that the delegates feel, but they're almost clinging to it in a way of consoling each other over a traumatic event for the country.

So, right now, it is a little bit more reserved than I see on the first day of convention.

But we have three more days to go.

And this party knows that they also have a very big task, a very tricky election for both parties involved this year.

And if the Republicans win, it will be in large part to the people who are here at this convention today.

AMNA NAWAZ: All right, that is our Lisa Desjardins live on the Republican Convention floor for us.

Lisa, thank you.

LISA DESJARDINS: You're welcome.