Michael Bloomberg decides against joining US presidential race

Michael Bloomberg, the former mayor of New York, has said he will not join the US presidential race for fear it would enable a victory by Republicans Donald Trump or Ted Cruz.

"That is not a risk I can take in good conscience," he wrote on Bloomberg View, an opinion website that is part of his media empire.

Bloomberg had been considering a presidential run, according to reports last month.

Combining business-friendly policies with liberal social views he would likely have appealed to centrist voters, although overall he had not received much interest from voters.

About 12 per cent of likely voters said they would support him in a three-way race for president with Democrat Hillary Clinton and Trump, according to a Reuters/Ipsos national poll conducted from Wednesday to Monday.