Former New York City Mayor Michael Bloomberg is preparing to file paperwork to qualify for the Democratic presidential primary in Alabama, although he has not officially decided to run.

“I know what it takes to run a winning campaign, and every day when I read the news, I grow more frustrated by the incompetence in the Oval Office,” Bloomberg wrote in March. “I know we can do better as a country.”

He added, “And I believe I would defeat Donald Trump in a general election. But I am clear-eyed about the difficulty of winning the Democratic nomination in such a crowded field.”

Bloomberg has floated the idea of a presidential run for several years, but initially bowed out of the 2020 election when former Vice President Joe Biden made it clear he would run.

Asked why Bloomberg changed his mind about Biden, an aide told Politico that “it’s not about any one candidate.”

The aide added, “He is worried about the state of the Democratic primary campaign and the possibility that we could lose in November. He wants to avoid that more than anything else.”

Bloomberg wrote in March, “It’s essential that we nominate a Democrat who will be in the strongest position to defeat Donald Trump and bring our country back together.”

SLIDESHOW: TOP DEMOCRATS RUNNING FOR PRESIDENT IN 2020

“We cannot allow the primary process to drag the party to an extreme that would diminish our chances in the general election and translate into ‘Four More Years,'” he added.

Bloomberg, whose net worth is an estimated $52 billion, would be the second billionaire to make a late entry in the contest, after investor Tom Steyer announced his bid over the summer.

Democratic candidate Bernie Sanders voiced his opinion after news about Bloomberg’s possible run surfaced, tweeting Thursday that “[t]he billionaire class is scared and they should be scared.”

Fellow candidate Elizabeth Warren tweeted, “Welcome to the race, @MikeBloomberg! If you’re looking for policy plans that will make a huge difference for working people and which are very popular, start here.” She then linked to a page that calculates what tax a billionaire would have to pay under her proposed wealth tax plan.

On this page, there was a special button that read “If you’re Michael Bloomberg click here.”

The next page congratulates Bloomberg on his extreme wealth and says, that he would pay $3.079 billion next year under Elizabeth’s wealth tax.

“This amount, which you likely won’t even feel, will help us invest in education from birth through college and help finance health care for everyone,” Warren’s page reads. “Good news — you’ll still be extraordinarily rich! And if history is any guide, if you do nothing other than invest your wealth in the stock market, it’s likely that your wealth will continue to grow.”