Weiner still on top in one poll. (Photo by John Moore/Getty Images)

A Quinnipiac poll of likely Democratic primary voters finds former congressman Anthony Weiner leading in the race for mayor of New York City.

The survey overlapped for only a day with the revelation that the married Weiner continued to engage in online sexual relationships after resigning from Congress, so the impact of that news is not really captured here.

The more interesting result in the poll is that former comptroller Bill Thompson is statistically tied with City Council President Christine Quinn and would beat her in a runoff. Those numbers suggest that, should Weiner take a beating for his personal behavior, Thompson would be the one to benefit.

Weiner leads with 26 percent in the poll, followed by Quinn at 22 percent and Thompson at 20. With Weiner out of the race, Quinn leads with 30 percent, followed by Thompson with 26. In a runoff, Weiner would tie Quinn. But Thompson would beat Weiner in a runoff 52 to 41 percent and Quinn 51 to 42 percent.

A candidate must take 40 percent of the primary vote to avoid a runoff between the top two vote-getters; in this crowded field that is very unlikely.

One thing that helps explain Thompson's edge over Quinn in a hypothetical run-off is that he's far more palatable, according to those polled. Asked if there's anyone they'd never vote for, 31 percent say they'd never vote for Quinn, but just 5 percent say the same about Thompson. In part that's because Quinn is much better defined. Fifty-one percent of primary voters say they know "just some" or "hardly anything" about Thompson, compared with 24 percent who say the same for Quinn.

A recent New York Times/Siena College poll gave Quinn the lead and had Thompson behind Weiner at 11 percent. But that survey was of registered Democrats, not specifically of likely primary voters.

Scott Clement contributed to this report.