On tonight's broadcast of MSNBC's "The Rachel Maddow Show," progressive firebrand Massachusetts Sen. Elizabeth Warren endorsed Hillary Clinton for President.

Rachel Maddow said, " I understand that you intend to endorse Hillary Clinton tonight, I'd like to hear it."

Warren replied, "Yea, I'm ready. I am ready to get in this fight and work my heart out for Hillary Clinton to become the next president of the United States — and to make sure that Donald Trump never gets anyplace close to the White House."

Here's a rush transcript:

MADDOW: Why did you not endorse during the primary? What was your thinking during the primary, holding out when so many other Democratic senators, all the women Democratic senators, almost all the men Democratic senators, got on board with Hillary Clinton -- Senator Sanders had Jeff Merkley. You were one of few holdouts who didn't endorse either one. What was your thinking about that?

WARREN: I thought that the primary was really important. And it was an opportunity for Democrats to get out there and show, this is what it means to be a Democrat. We got out there and pushed those issues forward and we made sure that the American people saw the kind of thinking we have, the kind of energy we have, and what makes us very different from those guys on the other side.

MADDOW: So, you think the primary was -- it was a long primary.

WARREN: I know that.

MADDOW: It was a tough contested primary. Some people worried that that was softening up the eventual Democratic nominee too much for the general.

But you think it was constructive?

WARREN: I do think it's constructive.

And I also think that what Bernie Sanders did was just powerfully important. He ran -- he ran a campaign from the heart. And he ran a campaign where he took these issues and he really thrust them into the spotlight.

And he also brought -- these are issues near and dear to my heart. And he brought millions of people into the political process. He brought millions of people into the Democratic Party.

And for me, that's what this is all about. I take my cue on every part of this from Bernie himself and what he said right at the beginning. He said, this campaign, he said, what this is about, what here doing here, is about millions of people across this country, millions of people who work hard every day and just keep getting slammed.

It is not about one candidate. It's not even about one election. It's about all of us coming together to help fight to level the playing field, to make sure that everybody gets a fighting chance.

MADDOW: Do you feel like Senator Sanders' supporters, and indeed Senator Sanders himself, who was independent until five minutes before this race, do you feel like they have a home in the Democratic Party right now, for real, or do you think the Democratic Party needs to do more, needs to change more, in order to be a natural home for those folks?

WARREN: The way I see this is that there is a very big and important home here. That I think about what's at stake in this election. And I think about what happens if the Republicans have the White House, the Senate, and the House of Representatives.

Say good-bye to the Affordable Care Act. That means 20 million people who lose their health insurance, just like that.

Say good-bye to Dodd-Frank and all of the financial reforms and efforts to try to rein in Wall Street. Just say good-bye to it. That means we can go where Wall Street gets to call the shots again. We saw how that worked out in 2008.

And say good-bye to a Supreme Court that is truly open and balanced and looking out for the American people. Instead the Republicans just want to capture a right-wing court for another whole generation.

I look at those things and I think about what's at stake. It's literally people's lives. It's our economy. It is the very fabric of our democracy. For me, that's the heart of what the Democratic Party stands for. That is what we fight for. That's why we're in this fight. That's why we've got to win.