The shift from Democrats was an ominous sign for the White House.
"I'm concerned about my integrity with voters who have returned me here 38 years. They know me enough to know I wouldn't purposely mislead them," Rahall said.
Republicans are already compiling lists of dozens of Senate and House Democrats such as Rahall who once repeated Obama's pledge that voters' existing coverage would not be canceled.
Top Democrats, who need to gain 17 seats to retake the majority in the House of Representatives, say next November's elections are far off. They say the health care law will be working well by then.
But America Rising, a Republican political action committee, is collecting video of Democrats' comments on the health care law. Some conservative groups are already running television spots, with Americans for Prosperity airing ads attacking Rahall and fellow Democrat Sen. Kay Hagan.
The health care law let insurers cancel some existing coverage that lacked the improved features that are now required. More than 4 million policyholders have received termination letters from their insurance carriers, according to an Associated Press count.
Obama on Thursday took administrative action to let insurers continue current plans for a year. He took the blame for the confusion.
Even so, most House Democrats felt Obama's action was not enough and demanded a vote on a Democratic proposal.
"They want to be on record," said Democratic Rep. Mike Doyle. "Members are not judged by administrative fixes. Members are judged by their voting records."
___
Associated Press writers Alan Fram, Henry C. Jackson and Laurie Kellman contributed to this report.