Self-identified pro-life Democratic senators Bob Casey of Pennsylvania and Joe Donnelly of Indiana didn’t say how they’d vote. North Dakota senator Heidi Heitkamp said during the 2012 campaign that she believes “late-term abortions should be illegal except when necessary to save the life of the mother,” but she too declined to take a position on the House bill.

Senate Democratic leaders have sent conflicting messages about whether they will allow a vote on a late-term abortion bill, and a Senate version of the House bill hasn’t been introduced yet. But if it does come up for a vote, it will force senators like Pryor and Landrieu to make a tough choice: Vote “yes” and anger the most powerful Democratic interest group or vote “no” and put themselves at odds with a clear majority of voters.

“You can’t get much more radical than opposing legislation that would protect women and babies from brutal late-term abortion beyond the fifth month of pregnancy,” says Marjorie Dannenfelser, president of the pro-life Susan B. Anthony List. “Not only is opposing this common-ground measure a moral mistake, it is a political one as well, especially for vulnerable senators in solid pro-life states.”

“That senators like Mary Landrieu would even hesitate to affirm this modest legislation shows just how beholden to the abortion industry many in the Senate have become,” adds Dannenfelser, whose organization spent $11 million on the 2010 midterm elections. “As the 2014 elections approach, we will be working to ensure that constituents understand just how outside the mainstream these four senators have become.”