NEW YORK (Reuters) - Michael Bloomberg, the billionaire media mogul and former New York City mayor, added his name to the Democratic primary ballot in Arkansas on Tuesday as he continued to publicly toy with running for president.

Bloomberg has not officially said whether he will run in the 2020 race, but has acknowledged he is considering a bid and qualified on Friday for the Alabama ballot. Each U.S. state conducts separate qualifying processes.

Bloomberg’s possible entry comes amid reports that former Massachusetts Governor Deval Patrick is also considering entering the Democratic race and a flurry of speculation that the party’s previous nominee, Hillary Clinton, may run again.

The heated talk of late entry by party stalwarts shows the volatility of the race, which already has nearly 20 candidates jostling for the party’s nod to run against Republican Donald Trump, even after more than a half a dozen other Democrats have dropped out.

It also highlights Democrats’ worries that the candidacy of frontrunner Joe Biden, who served as vice president under Democrat Barack Obama, may be weakening. The apparent ascendance of Massachusetts Senator Elizabeth Warren also worries many Democrats, who fear the liberal firebrand may not draw enough enthusiasm among moderate voters and Republicans who dislike Trump to propel a winning campaign against him.

On Tuesday, Clinton told a BBC interviewer that she was under “enormous pressure” from supporters to jump into the race for the party’s nomination, and declined to rule out the possibility when pressed. Still, Clinton said, “As of this moment...that is absolutely not in my plans.”

Patrick, the former governor, is considering jumping in, media outlets including the New York Times reported. His representatives did not respond to requests for comment from Reuters.

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If he were to run, Bloomberg would try to position himself as a moderate with a track record of success who could challenge Trump’s business experience.

While it is not required that a candidate appear in person, Bloomberg traveled to Little Rock, the Arkansas capital, to officially add his name to the state’s ballot, according to a Twitter post from the Arkansas Democratic Party.

Tuesday is the last day for candidates to qualify to be on the presidential primary ballot in Arkansas.

The decision to run would be an about-face for the 77-year-old Bloomberg, who said in March that he would not seek the White House.

Ranked by Forbes as the eighth-richest American, with an estimated net worth of $53.4 billion, his potential bid drew immediate criticism that he was just another wealthy businessman trying to buy an election.

His late entry into the race would force Bloomberg to play a quick game of catch-up to build the sort of campaign infrastructure his rivals have spent months constructing.

As a result, Bloomberg will skip early contests like the Feb. 3 caucus in Iowa and emphasize later voting states where his rivals will not have as big an organizing advantage, starting with the Super Tuesday primaries in at least 15 states, including Alabama and Arkansas, on March 3.

Biden, asked whether Bloomberg could successfully skip the four early states, argued it might not be possible to make up for lost ground.

“Michael is a talented man, has a little bit of money and can be engaged as long as he wants,” Biden said in Grinnell, Iowa, on Monday. “But I just think that the way the system is set up now, there are four gates you have to get through to get to Super Tuesday and on, and they are Iowa caucus, New Hampshire primary, Nevada caucus and South Carolina primary.”