Washington ? Republicans barely muscled a $450 billion debt limit increase through Congress on Thursday, finally resolving an issue that had become an increasingly difficult political burden for the GOP.

After weeks of saying they lacked the votes to win, top Republicans spent the day lobbying rank-and-file lawmakers and abruptly brought the bill to the House floor. The measure was approved by a mostly party-line 215-214, with just three Democrats and six Republicans defecting.

The Democratic-controlled Senate had approved the same increase in the borrowing ceiling on June 11 by a bipartisan 68-29 margin. President Bush is certain to sign it.

“The bipartisan House members who voted for this legislation put politics aside and did the right thing for the country,” Treasury Secretary Paul O’Neill, who had spent months urging congressional action, said after the vote. “They stood up for the soundness and strength of the American economy and preserved the full faith and credit of the United States government.”

No one doubted that eventually, Congress would raise the current $5.95 trillion debt limit to avert an unprecedented federal default.

But for months, Democrats used the issue as the symbol of what they say are President Bush’s failed fiscal policies, particularly the tax cut he pushed through Congress last year. The debt limit was last increased in 1997, before a string of four straight annual surpluses under President Clinton had allowed part of the debt to be paid down.

“Two Republicans, Mr. Reagan and Mr. Bush, they dug the hole,” Rep. Jim McDermott, D-Wash., said of the deficits that prevailed before then. “We dug us out of it and now you’re back into it. … Why don’t you admit you made a mess?”

Until Thursday, House GOP leaders said their plan was to win passage of the debt limit increase by including it in the popular counterterrorism package. But Democrats were eager to force a separate vote on the issue so in this fall’s congressional elections, their candidates could accuse Republicans of favoring federal borrowing to pay for last year’s tax cut.