NEW York Mayor Michael Bloomberg has ruled out an independent bid for the White House, averting what could have become a major upset to a two-horse presidential race.

'I listened carefully to those who encouraged me to run, but I am not - and will not be - a candidate for president,' he wrote in a New York Times op-ed piece.

The article put to rest a nagging uncertainty of the 2008 election season amid rampant speculation the 65-year-old billionaire businessman-turned-politician would mount a muscular independent bid that could influence the outcome of the presidential race.

Instead, he wrote: 'The most productive role that I can serve is to push them forward, by using the means at my disposal to promote a real and honest debate' and 'steer the national conversation away from partisanship and towards unity'.

The announcement brought a sigh of relief to the Democrats, who had been dreading a potential repeat of the 2000 presidential election when independent Ralph Nader helped President George W. Bush to his razor-thin victory by siphoning support from Mr Al Gore.

AGENCE FRANCE-PRESSE