A bare majority also support a ban on assault weapons.
The PPP poll found 39 percent say they would be less likely to vote for a candidate who had the NRA's backing, compared to 26 percent who say they'd be more likely to vote for a candidate with NRA backing.
The poll said 32 percent said it wouldn't influence them one way or the other. Among independents, 41 percent consider an NRA endorsement negatively compared to 27 percent who view it positively.
The PPP poll indicated 53 percent of voters say they support stricter gun laws in the country, compared to 39 percent opposed.
In a statement, PPP said the figures are basically identical to a 53/40 percent spread a month ago -- indicating the desire for stronger legislation has not receded as the Newtown, Conn., massacre fades from voters' minds.
The poll also said 51 percent of voters back an assault weapons ban, compared to 42 percent opposed.
Congressional Republicans saw some improvement in their support in the last month: They have a 22 percent approval rating with 68 percent disapproving -- up from a 15/75 spread a month ago, the poll said. Most of the improvement came from GOP voters, with anger over the fiscal cliff subsiding, the poll said.
On the immigration front, 64 percent of voters nationally think illegal immigrants should be given a chance to apply for citizenship, compared to 27 percent who think they should be deported.
PPP surveyed 800 voters nationally Jan. 31-Feb. 3 through automated telephone interviews. The margin of error for the survey is 3.5 percentage points.
PPP said the poll was not paid for or authorized by any campaign or political organization.