The disagreement poses a dilemma for supporters of gun control for which there is no clear answer: Is it better to teach wavering Democrats that there is a cost to voting against gun control, even if it jeopardizes Democratic control of the Senate, which is needed to enact gun control? Or is it better to maintain Democratic Senate control even if it means that some red-state Democrats are more likely to vote against gun control to protect their right flank?

President Obama took a position on this question in April, when he declined to lean heavily, or publically call out, the four Democratic senators who voted to block the expansion of background checks. While pundits attacked him as a weak leader, unable to sit down Alaska Sen. Mark Begich for a stiff drink, White House aides spoke privately about the importance of maintaining a Democratic Senate majority in 2014.

Since then, however, Obama’s own political organization, Organizing for Action (OFA), has promised to bring pressure on the four defecting Democratic senators—Pryor, Begich, North Dakota’s Heidi Heitkamp and Montana’s Max Baucus. Jon Carson, the head of OFA, has said his volunteers are less concerned about hurting the reelection chances of Democrats than getting a background check bill through Congress. In recent weeks, the group has held phone banks in Alaska, Arkansas and North Dakota to inform residents of their Democratic senators’ votes against more gun control. OFA volunteers have also protested outside Baucus’s office in Bozeman, even though Baucus has announced that he will not run for reelection after his term expires.