NEW YORK - New York City Mayor Michael Bloomberg has a wide lead in the November mayoral election campaign after his main rival officially entered the race, according to a poll published on Thursday.

Bloomberg, the billionaire founder of information and media group Bloomberg LP, leads Democratic challenger William Thompson by 52 percent to 36 percent, according to the Quinnipiac University poll carried out between September 16 and September 21.

New York Democrats last week chose Thompson, New York City's chief financial officer, to run against the independent Bloomberg.

Thompson, fresh from a big Democratic primary win, got no post-primary bounce in his campaign to unseat Mayor Michael Bloomberg, said Maurice Carroll, director of the Quinnipiac University Polling Institute.

Both Bloomberg, a former Wall Street bond trader, and City Comptroller Thompson, are trying to persuade voters they are qualified to lead one of the world's financial centre's out of the U.S. economic crisis.

According to Carroll; while Thompson is climbing the 16-point mountain... Bloomberg is rolling huge rocks -- in the form of a multi-million-dollar media blitz -- down on his head.

Bloomberg, whom Republicans have asked to run as their mayoral candidate, has already spent millions of dollars of his own money campaigning for a third term.

Forbes Magazine in March ranked Bloomberg the 17th richest man in the world and the richest man in New York with net worth of $16 billion.

The Quinnipiac University poll was the latest to show Bloomberg leading Thompson by a wide margin.

He is ahead of Thompson 75 percent to 12 percent among Republicans and 61 percent to 25 percent among independents, according to the poll of 1,513 New York City voters, which was the first Quinnipiac has carried out on the race.

Sixty nine percent of likely voters in New York City approve the job Bloomberg is doing, while 26 percent do not, the poll found. Thompson got 53 percent approval as comptroller, a job he has held since 2001, with 12 percent against and 35 percent undecided.

Among other contenders in the mayoral race, Conservative Party candidate Stephen Christopher has 2 percent support among those polled, with 9 percent undecided.

The survey had a margin of error of plus or minus 2.5 percentage points.

(Reporting by Tom Ryan; Editing by Andrew Hay)