New York, Nov 8 (IANS): Billionaire businessman and former New York City Mayor Michael Bloomberg was reportedly preparing to enter the Democratic race for the 2020 US presidential election, according to American media reports.

Bloomberg, 77, was preparing to file paperwork this week to declare himself a candidate in the Alabama presidential primary ahead of the state's filing deadline on Friday, Xinhua news agency reported citing the reports as saying on Thursday.

Bloomberg, who co-founded financial information and media company Bloomberg LP in 1981, was mayor of New York City from 2002 to 2013, serving three terms.

The move didn't necessarily mean Bloomberg was announcing a campaign, NBC News reported, citing a source close to the former Mayor.

Bloomberg is doing this to keep his options open, the source added.

In a series of tweets on Thursday afternoon, Howard Wolfson, a top advisor to Bloomberg, said the philanthropist "would offer a new choice to Democrats" if he decides to run.

"We now need to finish the job and ensure that (President Donald) Trump is defeated -- but Mike is increasingly concerned that the current field of candidates is not well positioned to do that," Wolfson said.

The advisor also noted Bloomberg's efforts in helping fund Democratic congressional and state legislative campaigns.

Bloomberg's net worth is $52 billion, according to Forbes magazine, which means he's one of the world's wealthiest individuals.

Currently, former Vice President Joe Biden is leading the 17-contender Democratic primary field by about 7 points with 27.6 per cent, according to the RealClearPolitics average of polling.

Biden was followed by Massachusetts Senator Elizabeth Warren with 20.4 per cent, followed by Vermont Senator Bernie Sanders with 17 per cent and Mayor of South Bend, Indiana, Pete Buttigieg with 7.1 per cent.