Christine Quinn, Anthony Weiner and Bill Thompson are running virtually neck-to-neck-to-neck in the New York City mayoral race, according to a Quinnipiac poll released Wednesday, one day after another survey put Weiner in first place.

Quinn, the City Council speaker, had 19 percent support among registered Democratic voters, compared with Weiner at 17 percent and Thompson at 16 percent, the Quinnipiac poll showed. Results for the three were within the 3.4 percentage point margin of error.

"This is a volatile, changeable election," poll director Maurice Carroll said. "We don't know who will win this election, but we do know there will be a runoff."

If no candidate reaches 40 percent in the Sept. 10 primary, the top two compete in an Oct. 1 runoff.

On Tuesday, a Wall Street Journal-NBC New York-Marist poll showed Weiner taking the lead from Quinn with 25 percent to her 20 percent.

Carroll theorized the discrepancy between the two polls was due largely to the timing. Quinnipiac polled voters June 19-25 after Thompson, a former comptroller, was endorsed by the influential United Federation of Teachers on June 19. Marist's survey was June 17-21.

advertisement | advertise on newsday

Thompson saw a 6 percentage point surge Wednesday compared with last month's Quinnipiac poll, but his chief strategist downplayed the jump.

"This race will be decided in late summer," Jonathan Prince said in a statement. Thompson "is always underestimated" and "always closes strong," Prince said.

Quinn spokesman Mike Morey brushed off the results in a statement, saying, "in the course of 24 hours, two separate polls have shown two separate things."

Marist Wednesday released additional data that showed Quinn, Weiner and Thompson within 2 points of each other in runoff scenarios.

Weiner's improved standing led a Republican contender, Joe Lhota, to pitch himself in a fundraising email as the candidate to stop Weiner, attacking him as having "resigned from Congress following an illicit sexual Twitter scandal and botched cover up."

In response, Weiner said Wednesday night that he has long been a target of "right-wing Republicans" and "I understand the idea that that's the way Republicans like to animate their base." As for the polls, Weiner said, "they're gonna go up, they're gonna go down."