Within minutes of Saturday’s historic House vote on health care reform, Republicans pronounced the political death of Rep. Thomas Perriello (D-Va.), pointing to the vulnerable freshman congressman’s vote in favor of the bill.

And in the aftermath of the politically charged vote, Perriello wasn’t the only Democratic congressman whose fortunes were being reassessed. The GOP, which voted nearly in lock step against the measure, began crowing about the demise of various other vulnerable members and seized on the moment as a milestone in the path back to a House majority.

Other than Perriello — who was the target of 12 consecutive postvote GOP e-mails accusing him of breaking his promises — a handful of members immediately stood out for casting especially tough votes...