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The billionaire former mayor of New York, Michael Bloomberg, is thinking about running for president as an independent candidate, US media report.

Unnamed advisers told the New York Times the 73-year-old sees a gap and has instructed staff to draw up plans.

Last year he commissioned a poll to see how he might perform against Republican frontrunner Donald Trump and Democratic favourite Hillary Clinton.

Mr Bloomberg would reportedly pump $1bn of his fortune into a campaign.

He has yet to make a statement on the issue but members of his staff have told other US media that he is indeed thinking about running, especially if Mrs Clinton is wounded by her rival Bernie Sanders.

The New York Times also reports that he has set a deadline for making a final decision in early March, when he could still enter the race in all 50 states.

The Republican and Democratic candidates face their first real test in just over a week, when Iowa becomes the first state to make its choice of nominee.

Analysis - Anthony Zurcher, BBC News, Washington

Michael Bloomberg is reportedly considering an independent bid for the presidency if Republican Ted Cruz or Donald Trump faces Democrat Bernie Sanders or a weakened Hillary Clinton.

Such a scenario could prove deadly for the Democrats. While Mr Bloomberg nominally holds no party affiliation and once was elected New York City mayor as a Republican, his candidacy likely would bleed support from the Democrats, and the Republicans he attracts would come from safely liberal states in New England, the mid-Atlantic and the West Coast.

It is a recipe for putting Donald Trump in the Oval Office with only a modest plurality of the vote.

Mr Bloomberg has embraced issues - gun control, climate change and sweeping public-health regulations - that are anathema to the right, no matter how palatable his pro-business policies may be.

While the former mayor may see this as a rare opportunity to run against flawed candidates from both parties ­and, in 2016, anything seems possible, his path to the presidency still would be a long shot.

It could end up creating an outcome where his dearest issues are actively undermined by the candidate who defeats him.