Transcript for Trump delivers first public speech since meeting with Kim Jong Un

Next to politics, president Donald Trump turning up the heat at CPAC. The conservative conference. In what may have been the longest speech of his presidency, president trump going after some of his favorite targets including Robert Mueller, James Comey and the Democrats now running for president. This as he tries to wrestled back headlines on the summit. Here's Tara Palmeri. Reporter: Tonight, after one of the most tumultuous weeks of his presidency, trump delivering one of his longest speeches ever, at times even profane. And all of the sudden, they're trying to take Y out with bull , okay? Reporter: With the special counsel's probe reportedly wrapping up, and Democrats promising even more investigations into the president and his inner circle, trump not holding back. There's no collusion. So now they go and morph into, let's inspect every deal he's ever done. We are going to going to his finances, we are going to check his deals, we are going to check -- these people are sick! They're sick. Reporter: Speaking for more than two hours before a crowd of supporters at a conservative conference in Washington. You know, I'm totally off script right now. And this is how I got elected, by being off script. Reporter: It was his first public comments since leaving a summit with Kim Jong-un without a deal to denuclearize the Korean peninsula. The president justifying why he defended the north Korean dictator over the death of 22-year-old American college student Otto Warmbier. And I'm in such a horrible position because in one way I have to negotiate. The other way, I love Mr. And Mrs. Warmbier and I love Otto. And it's a very, very delicate balance. Reporter: But for much of the speech, the president zigzagging from one topic to another. From his inauguration crowd size -- We had a crowd -- I've never seen anything like it. Reporter: -- To mocking former attorney general Jeff sessions -- And as you know, the attorney general says, "I'm going to recuse myself." Reporter: To why he fired James Comey. He's bad. He's a bad, bad -- he is a bad, bad guy. Reporter: At times, the president appearing to test out campaign talking points for 2020. I'm going to regret this speech. This speech should have been delivered one year from now, dammit. Reporter: Blasting the growing field of presidential candidates who want to take his job. I don't want to knock out all of the good stuff and end up with somebody that's actually got talent, that would be bad. Tara joins us now live outside the white house. This president delivering this speech. Tonight, some new reporting and Democrats escalating their efforts to get the president's tax returns. Reporter: Tom, house Democrats were initially going to wait for the Robert Mueller report to be handed over the department of justice. Now congressional aides say they're actively preparing a letter to the treasury department to get the president's tax returns. Michael Cohen's testimony has raised questions about whether the president inflated or deflated his income for tax Tara, thank you. This programming note, the latest on the investigation surrounding the president tomorrow morning on "This week."

This transcript has been automatically generated and may not be 100% accurate.