WASHINGTON — The Senate yesterday stalled a plan to open the Arctic National Wildlife Refuge to oil exploration, agreed to extend the life of the Patriot Act and passed nearly $40 billion in spending reductions in a furious pre-Christmas finish marked by testy floor debate and a rare tie-breaking vote cast by Vice President Dick Cheney.

Democrats and Republicans engaged in partisan brinkmanship to the very end over oil drilling and renewal of the Patriot Act, the post-Sept. 11 anti-terrorism law that expanded police powers to wiretap and obtain private records.

While the Senate split largely along partisan lines, the defection of a handful of maverick Republicans on each contested issue underscored how much difficulty President Bush now has holding his party's lawmakers in lockstep, which was the key to his success in Congress during his first term.

Losing the Alaska-drilling provision was a significant defeat for the Bush administration, which has made expanding oil exploration a centerpiece of its energy policy. It also was a personal blow to Sen. Ted Stevens, R-Alaska, the 82-year-old president pro tempore of the Senate who's battled to open the refuge to oil companies for 25 years.

Party leaders and key senators worked into the evening before salvaging a $453.5 billion defense spending bill that had been thrown into limbo because of the oil-drilling vote. In the end, the defense bill, which also contained $29 billion in aid for hurricane-damaged Gulf Coast states, passed 93-0.

That vote came after a much tighter, 48-43 vote to remove the oil drilling provision from the bill. What's more, the House of Representatives, which has adjourned for the year, must agree to the new version of the spending bill — a step it could take today by agreement of party leaders. If not, the Senate will have to reconvene tonight.

Cheney, who cut short an overseas trip to be at the Senate, rescued Republicans from an embarrassing defeat by casting the deciding vote in a 51-50 approval of the five-year budget reduction package. Five Republicans, one independent and all 44 Democrats voted against the cuts on the grounds that they were too hard on programs for the poor.

The budget vote was a long-sought victory for Republican fiscal conservatives, who'd insisted on cutting federal spending, in part to offset payments for post-Hurricane Katrina relief and rebuilding operations in Gulf Coast states. The House of Representatives, where fiscal conservatives mounted the budget drive, had passed $50 billion in reductions, but settled for the lower number in negotiations with the Senate.

Republicans, however, are planning to seek passage early next year of at least $56 billion in additional tax cuts over five years. More than offsetting the spending reductions, the net result would be a $16 billion increase in the projected $314 billion deficit for 2006, not the reduction that fiscal conservatives say they want.

The six-month extension of the Patriot Act came after Republicans repeatedly rejected requests for a three-month extension and represented a reversal for Majority Leader Bill Frist, R-Tenn., who had adamantly opposed a short-term extension. The deal came together with approval from the White House. The House of Representatives, which has adjourned for the year, would have to agree to it under a special arrangement.

Democrats and a handful of Republicans had wanted the time to negotiate more civil liberties protections into legislation renewing the act. Most of the current act's provisions would have been renewed permanently in the pending legislation.

But the vote with the broadest repercussions was the one that continues to block oil drilling in the Arctic National Wildlife Refuge, which had been tucked into the sweeping defense spending bill. To kill the drilling plan, opponents had to halt a vote on the entire Pentagon budget, which had been sweetened with $29 billion for post-hurricane relief and $3.8 billion to prepare for a potential influenza pandemic.

For two days, Stevens, a pugnacious master of Senate rules, wore the Incredible Hulk tie that he dons only when faced with difficult floor debate.

At stake are about 2,000 acres in the 19-million-acre refuge in Alaska's north slope that would be opened to oil drilling. The issue has symbolic impact far beyond its environmental consequences, pitting oil interests against environmentalists.

"We know this Arctic," Stevens said to his foes. "You don't know the Arctic at all."

Outside the chamber, environmental lobbyists lined up to keep pressure on Democrats to cast the difficult vote against the defense bill. Stevens needed 60 votes to end debate; he mustered 56, while 44 opposed him.

"This was going to be a sweating bullets kind of vote," said Athan Manuel, a lobbyist for the U.S. Public Interest Research Group, which opposes the refuge drilling.

The budget bill passed only after Democrats succeeded in removing some language from it, which will require another House vote for the modified bill. The House, however, has left for its holiday break and isn't scheduled to be back until Jan. 31.

The budget bill would reduce the growth of spending on Medicare, Medicaid, welfare and student loans. Democrats objected to the reductions, saying they targeted anti-poverty programs at the same time that Republicans were pushing tax cuts for wealthier Americans.

On Medicaid, the healthcare program for the poor, the bill would reduce benefits and require recipients to share some costs. It also would reduce the amount Medicaid pays for prescription drugs and would make it harder for the elderly to transfer assets to become eligible for Medicaid long-term care coverage. The bill reduces Medicaid spending by nearly $7 billion over five years.

The bill also reduces spending on Medicare, the health program for the elderly, by $6.4 billion over five years. Among its terms, it would require recipients to purchase, not rent, medical equipment under certain circumstances.

Students receiving college loans and their parents would have to pay higher interest rates and fees. The bill would reduce spending on student loans by $12.7 billion over five years.