Is Tierney next incumbent to go down?

Rep. John Tierney (D-Mass.) is locked in a margin-of-error race with primary challenger Seth Moulton in a new independent survey conducted under a week out from Primary Day.

{mosads}The survey, from Emerson College Polling Society, gives Tierney 47 percent support among likely primary voters to Moulton’s 44 percent support, within the poll’s 5-point margin of error.

It also shows Moulton more competitive in a general election matchup against Republican Richard Tisei, the presumptive GOP nominee. While Tierney lags Tisei by 8 points, with Tisei taking 51 percent, Moulton leads him by about that much, taking 44 percent to the incumbent’s 36 percent.

The survey is the latest indication Moulton could be surging heading into the final week of the race, which has become increasingly contentious in recent weeks. Tierney launched an ad this week tying Moulton to the NRA, the Tea Party and anti-abortion-rights Republicans, citing a contribution the candidate received from a political action committee that’s supported largely Republicans in the past.

Moulton, meanwhile, has been hammering Tierney as ineffective during his long tenure in Congress.

Tierney has long been considered one of Democrats’ most vulnerable incumbents after narrowly defeating Tisei last cycle amid controversy surrounding a gambling ring run by his family, but that situation has been less prominent in his primary fight this cycle. Instead, Moulton is looking to take advantage of a widespread anti-incumbent sentiment complicating the reelection prospects of incumbents nationwide.

The Interactive Voice Response survey was conducted among 500 likely voters and 343 likely Democratic primary voters from Sept. 2-4, and has an overall margin of error of 4.33 percent and a margin of error for the Democratic primary portion of 5.25 percent.