Trump’s impeachment trial in the Senate starts Tuesday afternoon. His defense team includes Ken Starr, the prosecutor whose investigation two decades ago led to the impeachment of President Bill Clinton, along with former Harvard law professor Alan Dershowitz.

Bloomberg and Trump both hail from New York and have long known each other. On Friday, the president criticized Bloomberg on Twitter, mocking his refusal to participate in the Democratic presidential debates.

Bloomberg spoke with NBC News during a campaign stop in Tulsa, Oklahoma, where he made a pitch to African American voters on Sunday, speaking about race-based economic inequality. He outlined a proposal aimed at increasing the number of black-owned homes and businesses, including a $70 billion investment in the nation’s most disadvantaged neighborhoods.

Bloomberg has been criticized for the stop-and-frisk policy he supported as mayor where New York City police officers made it a routine practice to stop and search multitudes of mostly black and Hispanic men to see if they were carrying weapons. He apologized for it in November, saying he got it wrong.

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"When we did it, it got out of control. When I noticed it, we did a little test of seeing what happens if you stopped it. Everyone said crime would go up. It didn't, so I said lets get rid of it," he said in the interview.

"When I left office, 95 percent of it was gone, and I wished I had apologized earlier. Plain and simple," he added.

The New York billionaire, who built his fortune through the financial information company he founded, only entered the race for the party’s nomination in November — a choice he made after looking at the other Democratic nominees.

“I looked, and I didn't think any of them could beat Donald Trump. Some, in fact, would almost guarantee his re-election,” he said of the other Democratic nominees, though he declined to name specific contenders.

Spelling out why he feels Trump is so dangerous, Bloomberg said that his impetuous style was hazardous for the country.

“It’s his process and lack of inclusiveness and getting advice from people. I always joke there’s no ‘I’ in the word team. The way Donald spells it, there’s no T, E, A or M, and that’s not the way to accomplish things,” he said.

Bloomberg has faced critical comments from other Democratic hopefuls on his large ad buys.

Massachusetts Sen. Elizabeth Warren said Bloomberg “plans to buy a nomination in the Democratic Party,” while Vermont Sen. Bernie Sanders accused him of using his billions to "buy the United States government."

In the NBC News interview, Bloomberg defended his ability to fund his campaign.

“They're not saying they're not going to spend money. They will spend every dime they can get. The difference is, I'm spending the money that I made,” he said.

“JFK was a millionaire, George Washington was a millionaire, Roosevelt was a millionaire. We have a history of wealthy people in — and I think those three are pretty good presidents, so you can't say it gives you bad presidents, at least not in those cases,” he added.

Bloomberg’s late entry into the nomination race meant that it was too late to build organizations in Iowa and New Hampshire and the other early states, he said. In the weeks since he declared his candidacy, he has built a sizable campaign operation, with many hundreds of staffers in dozens of states. The first test of Bloomberg’s electoral strength will be on Super Tuesday on March 3.

If he loses the Democratic nomination, that army of staffers would go on to help the eventual nominee, he has said.

Since entering the race in November, Bloomberg has hired more than 800 staffers, including 500 field organizers and staff in more than 30 states and another 300 staffers in his campaign’s New York headquarters.

He’s already unleashed more than $100 million on advertising and is on track to have a dozen offices in Ohio, nine in Michigan and 17 in Florida, his campaign has said.

The Associated Press contributed to this report.