Rep. Scott PetersScott H. PetersFix 340B drug discount program to increase patient access to treatment Reforming Medicaid’s drug discount program would be a real congressional achievement Stars of 'The Americans' talk US-Russia relations at DC premiere MORE (D-Calif.) has a narrow lead, near the margin of error, over Republican Carl DeMaio, according to a new poll conducted for the Democratic House Majority PAC.

Peters leads DeMaio by 48 percent to 43 percent in the survey, conducted by Democratic pollster GBA Strategies.

The poll shows warning signs, though, such as that Republican voters are more likely to turn out for midterms than Democrats, giving them an 8-point edge among likely voters. In the last presidential election, by contrast, President Obama won the district by 2 points.

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.