NEW YORK - (AP) - Democratic Rep. Anthony Weiner, months after hinting he probably wouldn't challenge Mayor Michael Bloomberg this year, has made it official.The congressman, who last year had been gearing up for his second mayoral bid, wrote in a New York Times op-ed that his decision not to run for mayor was final.

"I've taken stock of my life, my work in Washington and decided that now is not the right time to run," Weiner wrote in a piece posted on the newspaper's Web site Tuesday night.

Weiner, who represents parts of Brooklyn and Queens, said he wanted to focus on work in Washington, D.C., but acknowledged that the billionaire mayor's ability to forgo fundraising and finance his campaign with his own money contributed to his decision.

Bloomberg has already spent more than $18 million, nearly double what he had spent by this stage in his 2005 re-election campaign.

"With spending like that, regular debates about real issues will probably take a back seat to advertising .... the sad truth for a political candidate without deep pockets is that while money isn't the only thing, it does matter," Weiner wrote.

Weiner's announcement came several weeks after he had already told supporters he was rethinking his plans.

For much of last year when Weiner was mapping out his plans to run for mayor, Bloomberg was not a contender because the city's term limits law prohibited him from a third consecutive four-year term.

But in the fall, Bloomberg convinced the City Council to change the law so he could run again. At the time, Bloomberg argued that the change would give voters more choice.

The move upended the city's political landscape and changed the course of the mayor's race.

Since then, Weiner is the second major candidate to exit the field. City Council Speaker Christine Quinn, a Democrat, also had been widely believed to be planning a run for mayor, but she said she would instead run again for her seat.

Weiner ran for mayor in 2005 but narrowly lost the primary to Fernando Ferrer.