Soon the Senate will vote on legislation that would make abortions after 20-weeks illegal, honoring a promise that Majority Leader Mitch McConnell, R-Ky., made to social conservatives last year.

Because that legislation requires 60 votes before it can be taken up for consideration, chances of changing the law aren’t good. Parliamentary procedure and political arithmetic all but guarantee the U.S. will remain one of the seven nations that allow abortion past 20-weeks. But it’s far from an idle gesture.

With one floor vote, McConnell could lock in social conservative support and put red-state Democrats in a tough spot. What’s more, he has a good chance of single-handedly resurrecting extinct pro-life liberals.

At least two senators have already returned from the abyss. Sens. Joe Donnelly of Indiana and Joe Manchin of West Virginia have signaled their support for the bill. Come November, they will make the case to their constituents that they are pro-life Democrats (never mind that both voted to preserve federal funding for Planned Parenthood in 2015).

That leaves eight other senators on the bubble. As the roll call vote concludes, watch Democrats like Sens. Heidi Heitkamp of North Dakota and Claire McCaskill of Missouri. The more Trump won their state by in 2016, the more pressure they will feel to appease religious voters. Of course, that’s easier said than done.

Democratic abortion orthodoxy is unbending. There is no room for grace, as Tom Perez found out earlier this year. Less than 24 hours after the Democrat National Committee chairman endorsed Heath Mello, a pro-life mayoral candidate in Omaha, he was forced to reverse course and beg the party faithful for forgiveness.

The lesson was obvious: regardless of rank, political circumstance, or timing, obedience is always required.

It’s been that way for a long time, at least since 2003. As John McCormack of The Weekly Standard points out, the last Democrat moderates on abortion in the Senate had names like Sens. Joe Biden and Tom Daschle. But with a mix of election-year pressure, parliamentary maneuvering, and McConnell’s scheming, the pro-life Democrat might be resurrected for a time.