Tasked with limiting GOP defections, Minority Whip Eric Cantor (Va.) will continue holding the line for his Conference in the ongoing health care debate. But as Cantor has realized recently, keeping the GOP’s opposition unanimous is sometimes easier said than done.

After an intense lobbying campaign in the days before the recent tally, Cantor was unable to coax a “nay— vote out of Rep. Anh “Joseph— Cao (La.), an endangered GOP freshman whose New Orleans district has a nearly 30 percent poverty rate and legions of uninsured residents. Although Cantor persuaded Cao to vote after Democrats reached the 218th vote for passage, Cantor said recently that he “was disappointed— his colleague wound up supporting the Democratic bill, particularly because Cantor “worked with him constantly in the weeks before.—

The House’s health care vote was just the latest miscalculation by the GOP whip team. Over objections of GOP leaders, dozens of Republicans last month voted for hate-crimes protections, and eight GOP Members last summer voted for a highly contentious climate change bill. In the coming weeks, seven of those Members — Rep. John McHugh (N.Y.) recently resigned to become secretary of the Army — can expect frequent phone calls from Cantor if the evolving health care legislation becomes more palatable to GOP moderates such as Reps. Mike Castle (Del.) and Mark Kirk (Ill.), who are both seeking Senate seats in 2010.

Cantor also is predicting that Democrats are going to have their work cut out for them in the Senate unless substantial changes are made to the current legislation. But Democrats aren’t asking for his input, Cantor said. Although he is “hoping to have some role in shaping the policy— of the final legislation, Dr. No — as he’s known to his Democratic House colleagues — is doubtful that the majority will be soliciting his health care suggestions anytime soon.

“I’m going to work as hard as I can to make sure we don’t have any Republican support,— he said.