Anti-Trump Billionaire Tom Steyer hosts a town hall meeting on December 4, 2018 in Charleston, South Carolina. Steyer, founder of NextGen America and Need to Impeach, is testing the waters for a 2020 presidential run.

Billionaire and Democratic donor Tom Steyer will not be supporting Democrats who don't agree with him that President Donald Trump should be impeached, CNBC has learned.

In an interview Wednesday after Trump's former personal attorney Michael Cohen testified to the House Oversight Committee, the outspoken investor said he would not support any Democrats who do not align with his priorities of impeaching the commander in chief.

"If I believe he is the crisis and you want to be president of the United States and you want to push it off, I don't think you should be running for president in that case," he explained. "What I am saying is we aren't going to support someone for president who isn't for impeachment. That's not conditional," he later added.

When asked if any of the declared 2020 candidates match his determination to have the president impeached, Steyer said, "Not really." He noted, however, that former Texas congressman and U.S. Senate candidate Beto O'Rourke has been the rare lawmaker who appears to be on the verge of entering the presidential election and also supports the removal of the president.

"I think one of the people who is thinking about getting into the race is Beto O'Rourke, and he was for impeachment back when he ran for Senate," Steyer said. He made it clear, however, he was not ready to officially commit to supporting O'Rourke or anyone else in the next election.

Cohen himself brought up the 2020 elections during his closing remarks and painted a potentially grim picture if Trump ends up not winning a second term.

"I fear that if he loses the election in 2020, that there will never be a peaceful transition of power. And this is why I agreed to appear before you today," Cohen said of Trump at the time.

In a CNN town hall during O'Rourke's run for conservative incumbent Ted Cruz's Senate seat, the congressman was asked if he's changed his mind on impeaching the president, and he said, "I haven't."

"When, by broad daylight on Twitter, he asked his attorney general, Jeff Sessions, to end the Russia investigation, I would say that's obstruction in action," O'Rourke added.

The three-term representative fell to Cruz in the 2018 midterms by just under 2 percentage points but galvanized a quiet Democratic voter base in the deep-red state of Texas. He broke records in fundraising and youth voter turnout. Since his loss, he's been openly contemplating a 2020 run for president.

In a statement given to the Dallas Morning News, O'Rourke said he's made a final decision on his next steps, and the newspaper reported he has ruled out running against Texas Sen. John Cornyn.

Steyer has been one of the most vocal advocates of removing the president since Trump entered the White House. He too was considering a run for president after spending millions backing Democrats in the 2018 midterm elections, but he decided against the idea and chose to focus his efforts on his Need to Impeach campaign. He's committing $40 million to his latest phase of impeachment efforts and celebrated the Cohen hearing as a first major step toward that goal. His petition to impeach the president has over 7.4 million signatures.

"We got the first step of the truth out for everybody to see. I think we owe a huge debt of gratitude to Chairman Elijah Cummings. It's a first step and a great first step," Steyer said.