Anthony Weiner has vaulted to first place among Democratic mayoral candidates, with 25 percent to former front-runner Christine Quinn's 20 percent, according to a Wall Street Journal-NBC New York-Marist poll released Tuesday night.
Former Comptroller Bill Thompson placed third with 13 percent.
Weiner, forced to leave Congress in 2011 because of a sexting-and-lying scandal, joined the race just a month ago.
Quinn, the City Council speaker, led Weiner by 11 percentage points among Democratic voters in last month's Marist poll. Her support has eroded by almost half since a February Marist poll, held before Weiner hinted he would run.
Weiner said the poll results won't alter his course.
"In many ways it doesn't change anything. We're going to keep talking about ideas for the middle class and those struggling to make it," he said after a forum in Manhattan.
Fordham University political science professor Costas Panagopoulos said Weiner's name recognition means many voters have already decided about him, positively or negatively, while opponents are struggling to establish themselves. "In a primary with low turnout, high name ID is critical," Panagopoulos said.
The poll has a margin of error of 3.7 percentage points among Democratic voters.
On the Republican side, former MTA chairman Joe Lhota led billionaire John Catsimatidis, 28 percent to 21 percent, with 10 percent for George McDonald. The margin of error for the GOP sample is 8.8 percentage points.
The poll found Quinn trailing Weiner slightly among female Democrats, 22 percent to 21 percent. He led among blacks, Latinos and Asians.
The primary is set for Sept. 10, and if no candidate earns 40 percent of the vote, the first- and second-place finishers will meet in a runoff Oct. 1.
Quinn spokesman Mike Morey said in a statement, "We fully expect the polls to fluctuate throughout the campaign, but we are confident that on Election Day" voters "will choose someone who has demonstrated the ability to lead and deliver."
Quinn on Tuesday was endorsed by Service Employees International Union Local 32BJ, a building workers union with 75,000 members in the city.
With Matthew Chayes