Former New York Mayor Mike Bloomberg has been telling associates that he may actually run in 2020, as former VP Joe Biden struggles against Sen. Elizabeth Warren amid allegations of corruption in Ukraine and China, according to CNBC.

In private discussions, the 77-year-old signaled that he's "still looking at" running, though people close to him say he would only pull the trigger if Biden drops out before or during the early stages of the Democratic primaries. At that point, Bloomberg could replace Biden as a moderate with enough name recognition and financial backing to actually run. Bloomberg is estimated at $51 billion per Forbes.

"I think it’s something he wants. He has not been shy about that," a Bloomberg associate told CNBC. "Nothing can happen unless Biden drops out and that’s not happening anytime soon."

"He’s like everyone else. They can’t get it out of their system," said a banking executive who has known Bloomberg for decades, adding "Bloomberg is in if Biden is out."

During his three terms as mayor of New York, Bloomberg was a Republican and an independent. He registered as a Democrat, again, in October last year ahead of the party’s triumph in midterm congressional elections, during which Bloomberg was a big donor. He has said he would run as a Democrat if he pursued the White House this time around. Axios reported in April that Bloomberg might still run for president, despite his announcement a month earlier. Fox Business reported in September that he still has a team of political advisors and has kept the door open to running in 2020. -CNBC

Bloomberg considered a 2016 run, but announced that he wouldn't and instead endorsed Hillary Clinton. In 2012, he also considered a run but similarly decided against it - instead supporting Barack Obama.