Republicans in the Senate face a difficult but necessary vote in coming weeks to allow the Treasury to pad the $8.2 trillion national debt by another $781 billion.

The need to increase the legal limit on the debt has Democrats eager to use the debate to blast President Bush and his GOP allies in Congress for their fiscal stewardship.

"During this administration, America's debt, that is, the total of the deficits has increased by $3 trillion," said Sen. Max Baucus of Montana, top Democrat on the Finance Committee. "That's a 40 percent increase in the entire federal debt accrued by our country in its entire history."

Treasury officials briefed Senate staff aides Thursday and told them that without an increase in the government's ability to borrow, it would default on obligations for the first time in history sometime during the week of March 20. That is an unthinkable prospect that would roil financial markets and damage the government's credit rating.

Although Democrats recognize the need to avoid a default, they aren't likely to provide any votes to increase the borrowing limit. They are not responsible for the fiscal policies that produced it, Democrats argue, especially Bush's landmark $1.4 trillion 2001 tax cut bill.

"Every year that passes it becomes more and more apparent what a bankrupt strategy this is," said Sen. Kent Conrad of North Dakota, top Democrat on the Budget Committee.

Traditionally, when one party controls Congress and the White House, it falls to its members to muster the votes to pass debt limit increases.

"It's a vehicle for press releases but at the end of the day everybody knows you've got to do it," said Senate Budget Committee Chairman Judd Gregg, R-N.H. "The only other option is to shut the government down, and nobody who's a responsible policy person is going to do that."

Senate Majority Leader Bill Frist, R-Tenn., has yet to schedule debate on the bill. But if he follows past practice, he'll bring up the bill just before Congress leaves Washington on March 17 for a weeklong recess — when lawmakers are itching to go home and therefore tend to keep their pontificating to a minimum.

Conrad, Baucus and Democratic Leader Harry Reid of Nevada wrote Frist on Wednesday, urging him to schedule "a thorough and open public debate" on the debt limit bill.

"A substantial increase in the debt burden on American taxpayers is too important a matter to be rushed through the Senate without a complete debate on the current course of U.S. fiscal policy," the Democrats wrote.

They vowed to offer a longshot plan to reinstate so-called pay-as-you-go budget rules requiring tax cuts and new benefit programs to be financed by spending cuts or new revenues elsewhere in the budget.

Under an obscure House rule, that chamber gets to avoid having to vote on the debt limit if Congress successfully adopts a budget blueprint. So, after passing the budget last April, the House sent the Senate a $781 billion debt limit bill as if it had passed it separately.

That bill is the most likely vehicle for the Senate debate, but an alternative measure would be a filibuster-proof bill permitted under fast-track budget rules that limit debate and opportunities to offer amendments. But to go this route would require the House to vote on the bill before it is sent to Bush for his signature, a prospect House GOP leaders are eager to avoid.

"No decisions have been made," said Eric Ueland, chief of staff to Frist.

The last time Congress voted to increase the debt limit was in November 2004 when it was raised from $7.38 trillion to its current level of $8.18 trillion.