SAN FRANCISCO — Most San Franciscans believed their mayor would coast to reelection this November. They labored under this happy delusion because they were widely kept in the dark by the local press on just how problematic Gavin Newsom is for Gavin Newsom.

Indeed, tales of Newsom’s nights on the town are seeping out of City Hall fast now that it’s out that the mayor slept with his campaign manager’s wife. But that is only one part of Newsom’s problems. Key San Francisco power players cannot stand him and are gunning for him with a vengeance.

The list of people who have already declared publicly that they will work against Newsom’s reelection reads like a Who’s Who of San Francisco Power Players. First, there is Joe O’Donoghue, the head of the San Francisco Residential Builders Association (SFRBA). A classic Irish Democrat, O’Donoghue accumulated his fortune during the first real estate gold rush in the late 1980s. His SFRBA sits atop a pile of cash.

O’Donoghue is no fan of Newsom and has been writing poetry on SFRBA’s website that pitilessly mocks the mayor. One O’Donoghue poem implied that Newsom was a homosexual. This force of nature wants to bring down the mayor in the next election.

Then there is the veteran San Francisco political consultant Jack Davis. Davis has an instinctive knowledge of San Francisco and has knocked up so many political triumphs that he could quite possibly be called the man largely responsible for turning San Francisco into the far-leaning leftist town it is today. He usually gets his way, and unquestionably is a survivor.

It is a well-known secret that Davis has already begun to devise an anti-Newsom reelection plan that ingeniously makes use of the new San Francisco provisional voting system. Rumors have spread that he has promised to help Matt Gonzales, the man who almost beat Newsom four years ago, if Gonzales decides to run again. And Davis has made shocking overtures to get the more socially-conservative and fiscally-liberal, former Supervisor, Tony Hall, to enter the mayoral race.

After Newsom’s affair broke, Davis advised him to “resign and seek psychiatric help.” Davis wants Newsom gone — badly.

Don’t forget former Mayor Willie Brown. Brown, though a fellow Democrat, is not particularly enthralled by his successor. Telling the San Francisco Chronicle in January that the people in the Newsom administration “don’t fight,” Brown is rumored to be slightly still peeved that Newsom’s 2004 same-sex marriage gambit helped George W. Bush and the Republicans nationally. This can’t help Newsom with key Willie Brown allies, who aren’t likely to work for his reelection.

Factor in the opposition of politically well-connected property moguls and the mayor’s critics on the Board of Supervisors and Gavin Newsom is in for one hell of a ride.

But the mayor isn’t totally hopeless. Newsom remains above 50 percent in the polls He also has the benefit of two dedicated, up-and-coming power brokers on his side: chief political adviser Eric Jaye and lobbyist Darius Anderson. Both aim to eventually topple Jack Davis as the reigning King of San Francisco politics. Jaye is considered to be the closest to Newsom personally. Both he and Anderson are rising stars in the local — and perhaps national — Democratic Party.

Yet both Jaye and Anderson may lack a sufficient grasp of San Francisco. Old-time operatives criticize them for running campaigns that appeal only to the yuppie and bohemian elements of the city, as opposed to the more socially conservative parts. Sometimes their strategy works; sometimes, as in Janet Reilly’s 2006 Democratic primary race for the state assembly, it doesn’t.

With many critics and two major campaign operatives with spotty records, Gavin Newsom has a tough race ahead of him. It’s his to lose, and he just might. He’s in more trouble than anyone cares to admit.