Peters leads DeMaio by 48 percent to 43 percent in the survey, conducted by Democratic pollster GBA Strategies.
Peters's edge comes because he leads with the district's independents.
"Peters’ ability to maintain his current advantage will depend in large part on his ability to engage less consistent voters and ensure they come to the polls in November," a memo accompanying the poll said.
Partisan polls should always be taken with a grain of salt. The Peters-DeMaio race is expected to be one of the closest and hardest-fought in the country.
The live-caller poll of 400 likely voters, including one-third on cellphones, was conducted from July 20-22 and has a margin of error of plus or minus 4.9 percentage points.