'This Week' Transcript: Donald Trump, Reince Priebus, Denis McDonough, and Sen. Mitch McConnell

— -- THIS IS A RUSH TRANSCRIPT FOR 'THIS WEEK' ON March 20, 2016 and it will be updated.

ANNOUNCER: Starting right now on This Week with George Stephanopoulos, March Madness: now just three GOP candidates left standing as Donald Trump continues his march to the nomination.

DONALD TRUMP, 2016 REPUBLICAN PRESIDENTIAL CANDIDATE: We have a movement going on, folks. I will never let you down.

ANNOUNCER: But with his rivals and his party rallying to stop him...

SEN. TED CRUZ, (R) 2016 PRESIDENTIAL CANDIDATE: We are seeing Republicans uniting behind this campaign.

ANNOUNCER: Could a contested convention take Trump down? We're one-on-one with Donald Trump only on This Week.

Plus, Hillary takes aim.

HILLARY CLINTON, 2016 DEMOCRATIC PRESIDENTIAL NOMINATION: We should be breaking down barriers, not building walls.

ANNOUNCER: Hitting the GOP front-runner. Is Clinton already gearing up for a nasty November clash.

And supreme showdown inside the war over the president's Supreme Court nominee.

From ABC News, it's This Week. Here now, chief anchor, George Stephanopoulos.

GEORGE STEPHANOPOULOS: Hello again. After another wild week in the race for the White House, it began with more big wins for Donald Trump, at least three states on Tuesday, the most delegates by far, moving him much closer to the Republican nomination.

But as his campaign marches toward Cleveland, Trump drawing more protests, too. Check out this scene from Arizona yesterday. The road to a Trump rally blocked. And there are new questions overnight about how Trump and his supporters are dealing with those protests.

In Tuscon, this protester punched and kicked as he was lead away by police.

(BEGIN VIDEO CLIP)

UNIDENTIFIED MALE: The guy grabbed the sign out of my hand as I was being escorted out of the building and sucker punched me.

(END VIDEO CLIP)

STEPHANOPOULOS: And in this video from CNN, Trump campaign manager Corey Lewandowski appears to grab the collar of another protester who is also being pulled back by a member of Trump's private security team. A lot to talk about this morning with Donald Trump. He joins us now by phone.

Thank you for joining us this morning, Mr. Trump.

You know, so we saw these incidents in Tuscon last night. What more will you be doing to stop your supporters from acting out like this?

TRUMP: Well, it's not only in Tuscon. I mean, we had a great rally right next to Phoenix, and it was an amazing, 21,000 people. But the protesters block the road. So you had thousands of people that couldn't get in. Sherriff Joe, who did a fantastic job, immediately arrested three people and the rally totally broke up. It totally broke up. The people that were protesting. And they left. And they went. And there was no more problem.

And everyone went in. We had 21,000. There wasn't one word during this massive rally. And it was beautiful.

STEPHANOPOULOS: But what about this violence, Mr. Trump?

TRUMP: Then -- well, then a little bit later on we went to other areas I mean, we went all over -- Frankly, we went all over Arizona. And we went to Tuscon and we had some people that wouldn't allow people for the rally into the door. They were making it almost impossible to get in. We had 6,000 or 7,000 people at least. We had 2,000 people outside. They wouldn't allow them in.

These people are very disruptive (inaudible). These are not innocent (inaudible).

STEPHANOPOULOS: ...punching and kicking a protester?