The Senate voted in favor of the Medicare prescription drug bill (search) already approved by the House. The bill now goes to Bush for his signature.

Opponents tried — and failed — to get enough support for a procedural vote that would send the measure back to the drawing board.

After the final efforts to block the bill on Monday, Senate lawmakers agreed to hold a final vote Tuesday on the package designed to have the government co-pay seniors' prescription drug costs.

The Medicare drug benefit will help 42 million senior citizens get cost cuts on prescription drugs. Under the legislation, the prescription drug benefit (search) would begin in 2006.

In the interim, seniors will be eligible to purchase a Medicare-backed discount drug card at an estimated cost of $30 a year. The administration estimates this will mean savings of between 15 percent and 25 percent off retail prices.

Critics argue those estimated savings are wildly inflated.

The drug benefit makes for the most extensive overhaul of Medicare since the health-care program was created in 1965. It will provide subsidies to help lower-income seniors pay the premiums and other costs.

It also will provide subsidies to insurance companies in hopes they'll offer private coverage to seniors — a provision viewed with favor by conservatives but suspicion by many Democrats.

The $395 billion legislation — a top priority for President Bush — was passed by the House near dawn on Saturday in a 220-215 vote.

The Senate approval gave Bush and the congressional Republican majorities a significant legislative and political triumph on an issue that Democrats have long exploited in political campaigns.

Senate Majority Leader Bill Frist (search), R-Tenn., called it an "historic" and "momentous" day as lawmakers broke years of deadlock over revamping Medicare.

But Sen. Edward Kennedy, one of the legislation's staunchest foes, said the bill would ultimately cause "the unraveling of the Medicare system." He predicted Republicans would go on to attack Social Security after next year's election.

Bush was eager to sign the bill into law.

"Modernizing Medicare will make the system better and enable us to say to seniors we kept our promise," Bush said after visiting Army troops Monday at Fort Carson, Colo.

But even as the White House cheered the progress on the Medicare bill, Congress dropped efforts to pass major energy legislation this year — another Bush priority — after repeated attempts failed to find two additional votes needed to push the bill through the Senate.

At its heart, the Medicare legislation was designed as a compromise, with the new drug coverage for all Medicare beneficiaries long sought by Democrats combined with a Republican-backed plan to give private insurance companies a vast new role in health care for the program's beneficiaries.

The scope of the bill went far beyond prescription drugs, though, including an additional $25 billion for rural hospitals and health care providers, a requirement for higher-income seniors to pay more for Medicare Part B coverage and billions of dollars to discourage corporations from eliminating existing coverage for their retirees once the new government program begins.

The bill satisfies other goals of conservatives, including creation of tax-preferred health savings accounts open to individuals who purchase high-deductible health insurance policies.

Most contentious of all, the legislation creates a limited program of direct competition between traditional Medicare and private plans, beginning in 2010.

Conservatives argued that competition would help bring down the cost of Medicare over the long run, while critics said it would privatize the program and lead to "cherry picking" of relatively healthy seniors by insurance companies and higher premiums for those seniors who remained under the government-designed benefit.

Over and over, supporters of the bill stressed that after years of gridlock, the opportunity to act was at hand.

"If we don't do this at this time, it may be years" before another opportunity comes along, said Sen. Charles Grassley, R-Iowa, an architect of the bill.

Critics were unmoved. Senate Democratic Leader Tom Daschle called the bill a "bailout for the HMOs and insurance companies."

The bill's path to passage was cleared in the Senate on a pair of procedural votes, including a cliffhanger that was only decided when Sen. Trent Lott of Mississippi, the former Senate Republican leader, sided with the current GOP leadership despite his opposition to the legislation.