More importantly than that, it allowed them to pass it with a larger margin than a single vote.
A single vote would have allowed the Republicans to run ads against every single Democrat who voted for it saying that theirs was the vote that passed it.
If Nancy Pelosi does double-cross the pro-life Democrats and strip the pro-life language from the conference report, she would almost certainly lose at least 3 of the 42 members who voted both for Stupak amendment and final passage--enough to defeat the bill. So Democrats are left playing a game of chicken.
But if Republicans had voted down the Stupak amendment on Saturday night, they would have taken the issue off the table. "It would have looked extremely cynical," says Ponnuru. According to a House Republican aide, the "only message that would have come out of the Shadegg stunt is that Republicans only want to protect the unborn when they are in charge, but are willing to sacrifice them for political gamesmanship."
"If the Democrats had put up a phony amendment, that would be another story -- then we would have to call them out, but they did exactly what we asked. 183 Members, including Shadegg, asked for a vote on the Stupak amendment," the staffer added.
Senate Republicans could hardly have demanded that the bill bar federal funding of abortion after House Republicans had defeated the measure. Republicans would have been murdered in the press, and their pro-life reputations tarnished at least through the next couple election cycles.
Bringing down Stupak would have seriously hurt the effort to defeat Obamacare. The minority Republicans need public opinion and moderate Democrats on their side to defeat the health-care bill. Betraying pro-life Democrats and playing the part of cynical politicians for the media would have damaged that effort.