Billionaire businessman Michael Bloomberg is strongly considering entering the race for the US Democratic Party's presidential nomination.
The ex-New York City mayor is concerned the current field of candidates is not good enough to beat Donald Trump in the 2020 election, his spokesman says.
The 77-year-old is expected to file paperwork this week for the Democratic presidential primary in Alabama.
A total of 17 candidates are currently vying to take on President Trump.
Former Vice-President Joe Biden, Massachusetts Senator Elizabeth Warren, and Vermont Senator Bernie Sanders are the Democratic frontrunners.
Some recent opinion polls have suggested that Ms Warren and Mr Sanders - who are regarded as to the left of Mr Biden - might lose against Republican Mr Trump if either won the party's nomination.
Mr Bloomberg's spokesman said: "We now need to finish the job and ensure that Trump is defeated. But Mike is increasingly concerned that the current field of candidates is not well-positioned to do that."
Who is Michael Bloomberg?
Mr Bloomberg was a Wall Street banker who went on to found the financial publishing empire which bears his name. A philanthropist, he has donated millions of dollars to educational, medical and other causes.
Originally a Democrat, he became a Republican to mount a successful campaign for mayor of New York City in 2001.
He went on to serve three terms as mayor until 2012, rejoining the Democratic Party only last year.
Regarded as a moderate Democrat, he has highlighted climate change as a key issue, but he had appeared to dismiss a potential run for the presidency earlier this year.
Mr Bloomberg is a large financial backer of gun-control advocacy group Everytown for Gun Safety, which he helped found in 2014.
The group, and Mr Bloomberg were seen as playing a major role in a sweeping victory for Democrats in Virginia state elections earlier this week.
They vastly outspent gun lobby group the National Rifle Association - which is based in Virginia - by pumping $2.5m (£1.94m) into the state race.
