NEW YORK — Michael Bloomberg said Friday he won't endorse a candidate for New York City mayor, keeping his power and his wallet on the sidelines of the hotly contested race to succeed him.

That's a blow to Republican nominee Joe Lhota, an admirer of Bloomberg's policies who wanted his backing in hopes of thwarting the rise of the mayor's frequent antagonist, Democratic front-runner Bill de Blasio.

"I don't want to do anything that complicates it for the next mayor and that's one of the reasons I won't make an endorsement in the race," Bloomberg said during his weekly appearance on John Gambling's show on WOR Radio.

"I'll leave campaigning to the campaigners," the billionaire mayor said. "But whoever the voters elect, I want to make sure that person succeeds."

A top Bloomberg aide confirmed on Twitter after the show that the mayor would not endorse anyone before the Nov. 5 general election.

The radio show marked Bloomberg's first comments about the election since Tuesday's primary. He did not speak publically on the anniversary of the Sept. 11 attacks and did not take questions from reporters Thursday after a speech about the World Trade Center rebuilding process.

He stressed to Gambling that he made his decision to sit on the sidelines of the race because he has "never been a partisan guy."

But Bloomberg also may have wanted to avoid a repeat of the firestorm that erupted after his last comments about the race. In an interview with New York magazine published last weekend, Bloomberg said de Blasio's campaign, which is based on solving income inequality, was a form of "class warfare" and was "racist," because the public advocate used his biracial family in commercials.

Several Democratic primary voters said the interview made them more committed to supporting de Blasio.

De Blasio has not yet secured the Democratic nomination. He is hovering around 40 percent of the vote that would avoid triggering an automatic Oct. 1 runoff. On Friday, election officials will begin checking vote totals and will add absentee ballots on Monday.

The primary's second-place finisher, ex-comptroller Bill Thompson, has resisted calls to bow out in the name of party unity.

"As a democracy, our top priority must be that every vote be counted," Thompson said in a statement Friday. "Today we begin that process with the Board of Election's recanvass of all machine votes. We expect that process to move forward as accurately and expeditiously as possible."

Former congressman Anthony Weiner, who finished fifth on Tuesday, took to Twitter to suggest that if Thompson were to drop out he should "do it quick" or it would look "forced." Weiner was in a similar situation during his 2005 mayoral bid and dropped out to avoid a runoff with eventual nominee Fernando Ferrer.

De Blasio told reporters on Friday that Thompson had every right to want the vote counted, and said "I don't feel like I'm in limbo" though he does not know if his next electoral opponent will be Thompson or Lhota.

He also joked that he had been "waiting by the phone" for Bloomberg's endorsement. The mayor did not endorse anyone in the primary, but spoke favorably of City Council Speaker Christine Quinn, who finished third.

Bloomberg likely would have had a significant impact on the general election had he jumped in. Though polling suggests voters are ready for a change, Bloomberg continues to hold fairly high job approval ratings and could have used some of his $27 billion fortune on a candidate's behalf.

He also benefited greatly from an endorsement during his own first run for mayor. Bloomberg trailed Democrat Mark Green by double-digits in the polls only to surge when he received the public backing of then-Mayor Rudolph Giuliani in the days after the Sept. 11, 2001, terror attacks.

Giuliani had sky-high approval ratings in the aftermath of the attacks and the endorsement became a staple in Bloomberg's campaign ads. Bloomberg was elected with 50.7 percent of the vote.