Blumenthal’s lead in the U.S. Senate race has dropped by 1 percent since a survey released on May 27.
He now leads McMahon, 55 percent to 35 percent, according to a Quinnipiac University poll released on Thursday.
"Three weeks after the Vietnam flap, Attorney General Richard Blumenthal has lost a little more ground to Linda McMahon, but he still has a comfortable lead,” Quinnipiac University Poll Director Douglas Schwartz, said. “Prior to the Vietnam controversy, Blumenthal led by 33 points. A week after the controversy, his lead was 25 points. Now it's down to 20 points."
In the May 27 survey, Blumenthal led McMahon, 56 percent to 31 percent.
Blumenthal remains ahead of former U.S. Rep. Rob Simmons, 54 to 33 percent margin. Simmons suspended his bid for the GOP nomination but remains on the ballot.
Blumenthal’s lead over businessman Peter Schiff is 56 to 29 percent.
By a narrow 38 to 35 percent margin, Connecticut voters have a favorable opinion of McMahon, compared to a negative 32 to 39 percent favorability May 27.
This week, Republican women were successful in primaries across the county and, like those who won on Tuesday night, she is a successful businesswoman running as an outsider, according to Quinnipiac.
One difference, the poll notes, is that Connecticut voters have a negative view of the WWE and say that her experience as the World Wrestling Entertainment CEO makes them less likely to vote for her by about two-one margins.
"But McMahon must feel good that she has reversed her negative favorability rating," Schwartz said. "Blumenthal, meanwhile, still has a 73 - 22 percent job approval, the best score in Connecticut."
Connecticut voters say, 52 to 34 percent, that McMahon does not have the right kind of experience to be a U.S. Senator.
Because of Blumenthal’s statements concerning his military service in the Vietnam era, voters say 33 to 3 percent that they are less likely to vote for Blumenthal, but 61 percent say this doesn't make a difference.
"The Gulf oil spill washed the Vietnam flap out of the headlines, at least for now, possibly limiting the political damage for Blumenthal," Schwartz said.