WASHINGTON — Top Senate Democrats and Republicans said on Thursday that they had struck a deal to allow the debt ceiling to be raised through early December, temporarily staving off the threat of a first-ever default on the national debt after the G.O.P. agreed to temporarily drop its blockade of an increase.

Senator Chuck Schumer of New York, the majority leader, announced Thursday morning that he had reached an agreement with Senator Mitch McConnell of Kentucky, the minority leader, to clear the way for a vote on a short-term extension, with 11 days left before a possible default.

The movement came the day after Mr. McConnell backed down partially from his refusal to allow any such increase to move forward, offering a temporary reprieve as political pressure mounted to avoid being blamed for a fiscal calamity.

“It’s our hope that we can get this done as soon as today,” Mr. Schumer said on the Senate floor. He did not offer details about the agreement.

But the accord, which could be voted on as early as Thursday, does nothing to address the crux of the partisan stalemate over the debt. Republicans have not dropped their demand that Democrats ultimately use an arcane and time-consuming budget process known as reconciliation to lift the debt ceiling into next year.

“The pathway our Democratic colleagues have accepted will spare the American people any near term crisis,” Mr. McConnell said on the Senate floor. The extension, he added, also means “there’ll be no question they’ll have plenty of time” to use the reconciliation process to approve a long-term increase.

Democrats have so far refused, saying that the cumbersome process would take up too much time and that Republicans should help accommodate debt stemming from policies approved by both parties.