(CNN) - A new poll indicates that the battle for Connecticut's open Senate seat is becoming more competitive, as is next week's Republican Senate primary.
According to a Quinnipiac University survey released Tuesday, 50 percent of Connecticut voters say they back longtime state Attorney General Richard Blumenthal, the presumptive Democratic nominee, with four in ten supporting former professional wrestling executive Linda McMahon, the leading GOP Senate candidate, and seven percent undecided.
Blumenthal's ten point advantage is down from a 17 point lead in a Quinnipiac poll from last month and a 20 point margin from June.
"The McMahon-Blumenthal Senate race in Connecticut could be a real smackdown, as the Republican has the money and momentum, cutting into Blumenthal's lead month to month," says Quinnipiac University Poll Director Douglas Schwartz. "Independent voters, the largest bloc of voters in Connecticut, are for the first time evenly divided between Linda McMahon, who gets 46 percent, and Richard Blumenthal, who gets 44 percent. Blumenthal led 54 – 35 percent among independent voters just three weeks ago."
The general election winner will succeed five-term Democratic Sen. Chris Dodd, who announced earlier this year that he would not run for re-election. A GOP Senate victory in Connecticut would give the party a big boost towards possibly reclaiming control of the chamber.
The poll release comes six days before the state's primary. According to the survey, McMahon leads former three-term Rep. Rob Simmons 47 to 30 percent, with businessman Peter Schiff at 14 percent. McMahon's 17 point advantage over Simmons is down from a 27 point margin last month.
Since then, Simmons has jump started his campaign. The former Army officer, decorated war veteran, and CIA employee, suspended his campaign and released most of his staff after McMahon captured the Senate nomination endorsement of Connecticut Republican delegates at the state's GOP convention in May. The gathering gave Simmons a second place finish and businessman Peter Schiff was third in the voting.
But Simmons remains on the primary ballot, and in recent weeks he has gone up with campaign television commercials, attended a debate, and has scored the endorsement of a number of Connecticut newspapers, including the Hartford Courant, the largest newspaper in the state.
"As McMahon focuses on Blumenthal, she better watch her back. Rob Simmons has shown surprising strength among Republican voters after jumping back into the primary contest barely two weeks ago. But it might be too little too late for Simmons," adds Schwartz. "Among all voters, McMahon runs better than Simmons against Blumenthal, which is different than our last poll when they ran roughly the same against Blumenthal. Republican primary voters think McMahon has the better character and personality to be a U.S. Senator, but that Simmons is more qualified."
The Quinnipiac University poll was conducted July 28-August 2, with 1,299 Connecticut voters questioned by telephone. The survey's overall sampling error is plus or minus 2.7 percentage points. Quinnpiac conducted a separate survey of 1,003 likely Connecticut GOP primary votes, with a sampling error of plus or minus 3.1 percentage points.
Follow Paul Steinhauser on Twitter: @psteinhausercnn