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When Democratic Senator Mark Pryor of Arkansas voted against a gun background check compromise last month, he was taking a measured political risk. Even as Mayor Michael Bloomberg's anti-gun group announces a plan to spend $350,000 on ads criticizing Pryor, a detailed new poll walks through why it may have made political sense. With another vote on the issue a near-certainty, gun control advocates are fighting to change that calculus.

Conducted by Pew Research, the survey is one of the most comprehensive analyses gun control politics that's come out since the president's renewed focus on the issue. In April, a key component of his effort — a package of policies including background checks, funding for school safety, and increased penalties on trafficking — never received a vote in the Senate after a Republican-led filibuster of a compromise on background checks wasn't ended. That vote was where Pryor bucked his party: he was one of four Democrats to support the filibuster out of principle, helping to ensure that the policy was blocked on a 54 to 46 vote.

The policy, which would expand background checks for gun sales at shows and for private dealers, is one that voters broadly supported at the time — and continue to support. Pew's analysis starts by asking about various policy proposals. Expanded background checks are by far the most popular, regardless of political party.

