A new GOP poll shows Rep. John F. Tierney, D-Mass., and his likely rematch opponent, Republican Richard Tisei, in a statistical dead heat.

The 6th District survey showed Tisei with 42 percent and Tierney with 40 percent — a minor lead within the poll’s margin of error of 4.8 percent.

The National Republican Congressional Committee paid for the survey, which was given exclusively to CQ Roll Call. Harper Polling, a conservative firm, conducted the automated poll that surveyed 416 likely voters from July 29-31.

Last cycle, Tierney beat Tisei by a 1-point margin, and President Barack Obama carried the district with 55 percent. Tierney’s win came as a shock, as polls had Tisei in the lead in the weeks leading up to the election.

This cycle, Tierney also faces a Democratic primary challenge from former Marine Seth Moulton.

The 6th District is rated a Lean Democrat contest by Rothenberg Political Report/Roll Call.