WASHINGTON – House Democrats said Wednesday that President Obama should invoke a little-known constitutional provision to prevent the nation from going into default if Congress fails to come up with a plan to raise the debt ceiling.

Rep. James Clyburn of South Carolina, a member of the Democratic leadership, said he told fellow Democrats that Obama should both veto any House GOP plan for a short-term extension of the debt ceiling and invoke the 14th amendment, which says that the validity of the nation’s public debt “shall not be questioned.”

The White House has rejected resorting to this tactic to keep the nation from defaulting, questioning its legality, but Rep. John Larson of Connecticut, who chairs the Democratic caucus, said “we’re getting down to decision time” and “we have to have a failsafe mechanism and we believe that failsafe mechanism is the 14th Amendment and the president of the United States.”

Larson said Clyburn’s proposal on the 14th Amendment was met with applause by other Democrats at their meeting.

White House spokesman Jay Carney, asked about Clyburn’s proposal, said only Congress has the authority to extend the government’s borrowing authority. “The president does not have authority to raise the debt ceiling. It’s not a plausible way to address this problem and we do not think it is an option,” he said.

The post-Civil War 14th Amendment guaranteeing citizenship to all people born or naturalized in the United States contains a provision that “the validity of the public debt of the United States, authorized by law, including debts incurred for payment of pensions and bounties for services in suppressing insurrection or rebellion, shall not be questioned.”

Some legal scholars have said the president can invoke that clause to keep the nation from defaulting on the debt, although there is no legal precedent.