Former New York City Mayor Michael Bloomberg officially entered the very crowded Democratic presidential race over the weekend.

It's a race that's been well underway since the start of the year.

MORE: Former NYC Mayor Michael Bloomberg launches Democratic presidential bid

Bloomberg was seen leaving his home Monday, but refused to answer any questions from reporters.

The self-made billionaire announced that he was throwing his hat in the ring Sunday with this tweet saying, "I'm running for president to defeat Donald Trump and rebuild America."

The former three-term mayor is billing himself as a problem solver and one who can take on Donald Trump.

Sen. Chuck Schumer says he is supporting Bloomberg's decision to enter the race. But Sen. Bernie Sanders says multimillionaires like Bloomberg are not going to get very far in the election.