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 adviser says.

The 77-year-old is expected to file paperwork this week for the Democratic presidential primary in Alabama.

A total of 17 Democratic candidates are vying to take on President Trump.

Former Vice-President Joe Biden, Massachusetts Senator Elizabeth Warren and Vermont Senator Bernie Sanders are the 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.

So far, three Republicans have said they will challenge Mr Trump in the party's primary contest.

But it is seen as almost impossible that anyone will take the Republican mantle from the president.

What did Bloomberg's adviser say?

In a statement, Howard Wolfson 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.

"Based on his record of accomplishment, leadership and his ability to bring people together to drive change, Mike would be able to take the fight to Trump and win," Mr Wolfson said.

President Trump, 73, has so far made no public comments on the issue.

The Democratic nominee for the presidential election on 3 November 2020 will be selected after a series of electoral contests across the country.

In Alabama, candidates must by Friday submit the necessary paperwork to get on the Democratic primary ballot.

If Mr Bloomberg does indeed enter the race, he will still have to register in other states which have later filing deadlines.

A New York billionaire as president?

So far this is only a single toe entering the water, but it's a significant one. The presence of the former New York mayor and multi-billionaire would set alight the race for the Democratic Party nomination.

The politician closest to Mr Bloomberg's centrist outlook is Joe Biden - but his campaign appears to be fading.

Mr Bloomberg has, I understand, been doing a lot of polling in early voting states like Iowa and New Hampshire.

This isn't the first time that he's eyed a run at the presidency, only to eventually decide against.

But in the past he's ruled himself out because he thought Americans wouldn't vote for a billionaire New York businessman. That concern no longer applies.

Who is Michael Bloomberg?

Mr Bloomberg's net worth is $52bn (£40bn), according to Forbes. This is nearly 17 times more than that of Mr Trump ($3.1bn).

Mr Bloomberg was a Wall Street banker who went on to found the financial publishing empire that 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.

 

 

From friends to bitter rivals: Michael Bloomberg (left) and Donald Trump

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 into the state race.