The race for outgoing Massachusetts Democratic Rep. John Tierney's seat is neck-and-neck, according to a poll conducted for a Republican group that plans to spend $500,000 on the race.
American Unity PAC, a super PAC that backs Republicans who support same-sex marriage, released a poll conducted by Voter Consumer Research showing Republican former state Sen. Richard Tisei with a 2-point edge -- within the poll's margin of error -- in the race for Tierney's seat. Tisei led Marine Corps veteran Seth Moulton, who beat Tierney in the September Democratic primary, 44 percent to 42 percent. The survey polled 400 likely voters from Oct. 6th to Oct. 9th and had a margin of error of 4.9 percentage points.
Jeff Cook-McCormac, a senior advisor for the PAC, said in the statement that it would spend "at least $500,000" backing Tisei, and called on other groups to also jump in the race.
"Richard Tisei is leading and poised to win this race; we look forward to others joining the fight," he said.
Tisei is one of only three openly gay Republicans running for Congress this cycle. The group is also backing former San Diego City Councilman Carl DeMaio in California's 52nd District, and supported former University of New Hampshire business school Dean Dan Innis, who lost in the Republican primary in New Hampshire's 1st District, among other Republicans who back same-sex marriage.
Tisei may have been the favorite to beat Tierney in the general election. He lost to him by only a few thousand votes in 2012, and Tierney has been hampered by bad press about his wife and brother-in-law going to prison on charges of running an illegal offshore gambling business. The hope among Democrats is that Tisei will have less to run against in Moulton, a political newcomer who served four tours in Iraq.
"Senator Tisei has spent 30 years as a Republican political insider," said Moulton campaign spokesman Carrie Rankin. "The last thing voters want is another career politician representing them in Washington. Seth supports a new vision for the district, a commitment to standing up to the extremists and fighting for the values of hardworking Massachusetts families."
Previous polling in the 6th District race has been all over the map. A Garin-Hart-Yang Research Group poll conducted in late September for House Majority PAC, the major Democratic House super PAC, showed Moulton with a 10-point lead 43 percent to 33 percent. An Emerson College robopoll conducted around the same time also showed Tisei with a 2-point lead. A Tarrance Group poll conducted for Tisei's campaign also showed the candidates within the margin of error, with Tisei holding a 1-point lead. But a WBUR poll showed Moulton with an 8-point lead. And two automated Democratic polls conducted earlier in September showed Moulton with leads of 8 points and 18 points.
The American Unity PAC poll did not include independent candidate Chris Stockwell, who earned 11 percent in House Majority PAC's poll. Tisei campaign spokesman Charlie Szold said after the release of House Majority PAC's poll that he expects Stockwell to pull more votes from Moulton than from Tisei.
The district favors Democrats, but less so than most of the state. President Obama won there by an 11-point margin in 2012.
Update: This story has been updated with a statement from Moulton's campaign.
Jack Fitzpatrick is a staff correspondent at National Journal. He has previously written for USA TODAY, NBCNews.com, Slate, The Arizona Republic and other newspapers and websites. He graduated from Arizona State University with a master's degree in mass communication and a bachelor's degree in journalism.