Updated

Senators were gearing up Saturday for what is expected to be a battle over Medicare (search) prescription drug legislation that narrowly passed the House earlier in the day.

Democratic members of the Senate were crying foul about tactics used by House Republicans to ensure the bill's passage. The House debated the package from dusk until dawn early Saturday, with the bill finally gaining approval after the longest roll call vote in the history of the chamber.

Now, some senators say they'll try to stall the bill, which would give 40 million older and disabled Americans a prescription drug benefit and a new option for private health care coverage. Two lawmakers promised to stage a filibuster to prevent a vote on the legislation.

President Bush lauded the GOP-controlled House for approving the bill, which passed by a vote of 220-215. Bush, eager to sign the bill and use it as a sign of his success as president while campaigning, urged the Senate to follow the House's lead.

"We're on the verge of success" of modernizing and strengthening Medicare, Bush said Saturday in his weekly radio address.

Soon after Bush's address, senators launched into a debate over the bill that could last as many as three days. Sixty votes in favor of the bill are necessary to halt debate and hold a final vote on the bill.

To pass the bill, Republican leaders held open the House vote for nearly three hours while trying to win votes of Republican holdouts. Supporters of the bill said the Senate, unlike the House, would not be dogged by such a drawn-out partisan struggle.

"I think you'll see an entirely different atmosphere in the Senate," said Sen. John Breaux (search ), D-La., one of the architects of the compromise.

But both Senate lawmakers from Massachusetts begged to differ. Democratic Sens. Edward M. Kennedy (search) and John Kerry (search) promised to filibuster.

Kennedy said the House vote was similar to the disputed 2000 presidential election in Florida. "It was a rigged vote," he told reporters in his Capitol hideaway office. "Give this bill a fair vote in the House of Representatives and I'll drop my filibuster."

Senate Democratic leader Tom Daschle (search) of South Dakota, however, said he is opposed to a filibuster, even though he plans to vote against the bill.

Senate Majority Leader Bill Frist (search), R-Tenn., said he would seek a vote Monday to stop a filibuster, adding that he hoped Kennedy would reconsider.

"There is a strong bipartisan majority in this body, in the U.S. Senate, in favor of the Medicare prescription drug legislation," Frist said.

Republican plans to pass the bill and send it to the president before Thanksgiving were nearly thrown into disarray by the House vote.

The outcome remained unsettled until just before 6 a.m. Saturday, when Republicans finally overcame a rebellion by conservatives in their own ranks and the overwhelming opposition of Democrats.

Roll call votes in the House customarily last 15 minutes to allow lawmakers ample time to reach the chamber.

"In the end, democracy works," said Rep. David Hobson, R-Ohio, as weary Republicans marked their overtime victory.

House Democratic leader Nancy Pelosi of California countered, "We won it fair and square and they stole it by hook and crook."

Dozens of lawmakers, participants and spectators both, waited out the drama of the middle-of-the-night roll call.

Hastert, his lieutenants and Health and Human Services Department Secretary Tommy Thompson (search) shuttled from one GOP holdout to another seeking enough votes to prevail. The president lobbied about a dozen lawmakers by phone from the White House late Friday and early Saturday.

Frist said he awoke twice in the middle of the night to check the progress on C-SPAN. "I got up at 5, saw the vote on the screen and said, 'Oh my goodness,"' he said.

The vote was stuck at 216 to 218 for over an hour, the bill seemingly on its way to defeat before a flurry of last-minute switches.

"I did not want to vote for this bill," said Rep. Butch Otter, R-Idaho. But he did, as did a handful of late GOP converts.

He said afterward he became convinced that if the measure were defeated, another one would come back to the House floor even less to his liking.

The bill drew the support of 204 Republicans and 16 Democrats, many of whom waited until the bill appeared on the verge of passage in the final moments of the roll call before swinging behind it. Voting no were 189 Democrats, 25 Republicans and 1 independent.

As written, the legislation would virtually remake Medicare.

For the first time, the legislation would also require those older Americans with annual incomes over $80,000 to pay higher premiums under Medicare Part B, which covers services outside the hospital.

Additionally, it would establish new tax-preferred health accounts, open to individuals with high-deductible insurance policies.

The tax provision and the requirement for higher premiums were part of an effort to appeal to conservatives who favor transforming Medicare and restraining its cost, yet find creation of the new prescription drug benefit distasteful.

Many Democrats argued that some of the conservative-backed elements of the bill were too dear a price to pay for the drug benefit — particularly a provision creating a limited experiment in direct competition between private plans and traditional Medicare beginning in 2010.

The Associated Press contributed to this report.