Massachusetts Republican Richard Tisei's rematch Rep. John Tierney (D-Mass.) could turn out differently this fall, according to a new poll.

Tisei, the GOP's 2010 nominee, leads Tierney 45 percent to 40 percent in the Emerson College Polling Survey released Wednesday. The five point lead is a bump for Tisei from an April poll showing the two candidates tied at 44 percent of the vote. 

There is good news for Tierney though -- is the poll still finds him easily topping his primary competitors, holding 59 percent of the vote. Former Marine Seth Moulton, Tierney's closest primary challenger, had 17 percent, while his other two competitors, Marisa DeFranco and John Devine, failed to break single digits. 

Despite his solid lead ahead of the September 9 primary, it's still a five-point drop in support for Tierney and a 6-point gain for Moulton from the April survey. 

The Emerson poll shows Tierney's standing has dropped in the district. Only 34 percent of respondents believe he should be reelected compared with the 53 percent that do not. Still, even with these numbers, 46 percent of voters polled still expect Tierney to win in November. 

Tisei and Tierney first faced off in 2012, where Tierney narrowly pulled out a narrow victory. 

The Emerson poll used an interactive voice response system to survey 253 likely voters. It was conducted from June 12-18 and has a margin of error of plus or minus 6.12 percentage points.