After watching the race nearly become a dead heat, Democrat Richard Blumenthal has opened a double-digit lead over Republican Linda McMahon in their U.S. Senate contest, according to a Quinnipiac University poll released today.

A new poll of likely voters found Blumenthal preferred over McMahon, 54 percent to 43 percent, nearly quadrupling from his lead from 3 percentage points to 11 percentage points since Quinnipiac’s previous poll two weeks ago.

“Fueled by a surge in support from women, Democrats and independents, Attorney General Richard Blumenthal has his best poll numbers since the start of the fall campaign,” said Douglas Schwartz, the poll’s director.

Both Blumenthal and McMahon got increased support from their own parties, while voters who identified themselves as independent reversed, from favoring McMahon by 49 percent to 44 percent to backing Blumenthal by the same margin.

The poll ends what had been a steady erosion of support since January in Quinnipiac polls, first on surveys of all voters and more recently in polls focusing on likely voters. Other polls, however, had shown Blumenthal with more comfortable leads.

Still, the survey should provide comfort to Democrats who nervously waited for their best-known candidate on the ballot, who entered the race in January as the presumptive favorite to succeed retiring Sen. Christopher J. Dodd, to stabilize in the Quinnipiac poll.

For different reasons, each campaign downplayed the poll.

“We have always said this election will be close, and as is typically the case in close elections, polling will fluctuate,” said Ed Patru, the communication director for McMahon.

McMahon’s support eroded after her gaffe two weeks ago in failing to clearly answer questions about the minimum wage. She left a press conference refusing to rule out supporting a cut in the minimum wage, though she quickly clarified that was not the case. The episode quickly became featured in a Blumethal ad.

“While those attacks did have a temporary impact, it’s very clear to us that this race has stabilized and voters are once again focused on economic recovery and job creation,” Patru said.

Mindy Myers, Blumenthal’s campaign manager, said, “We will continue to work like we are 10 points down, because there is a lot at stake during this election and with our opponent spending $50 million to fuel her negative attack machine we know that this is going to be a tough race until the very end.”

Blumenthal, the state’s longest-serving attorney general, has been under an onslaught of critical television commercials from McMahon, the former World Wrestling Entertainment executive.

Waging Connecticut’s most expensive campaign, commercials praising her as a political outsider and savaging Blumenthal as a career politician who has misstated his Vietnam military history can be seen several times an hour.

“Linda McMahon may have peaked too soon and her advertising saturation could be causing ‘McMahon fatigue,’” Schwartz said.

Blumenthal has maintained a job approval rating of 69 percent to 26 percent, and by a margin of 57 percent to 38 percent, likely voters say they still have a favorable opinion of him.

“Blumenthal is running stronger among Democrats than McMahon is running among Republicans. He is winning women by an overwhelming 31-point margin, while McMahon has struggled with women throughout the campaign. They have a negative image of her but like him by more than 2-1,” Schwartz said.

Voters are split on McMahon, with 46 percent saying they have a favorable opinion and 46 percent saying they have an unfavorable opinion.

“With only three weeks left in the campaign, McMahon is down by 11 points with only 3 percent undecided,” Schwartz said. “Even if she won all the undecided, she still would fall short. This has been a very unusual election year, however, so anything is possible.”

The poll was based on a telephone survey of 1,119 likely voters conducted from Oct. 7 to 11. It has a margin of error of plus or minus 2.9 percentage points.