Updated from 2:06 p.m. EST

Senate backers of an ambitious bill to reform the government's Medicare program defeated an attempt to block a vote via filibuster Monday, and the measure appeared destined for passage.

A motion to end debate on the measure was passed 71 to 29, essentially ending the threat of filibuster, and a roll-call vote came out in favor of passage late Monday. Now that a filibuster is out, the bill's backers are thought to have more than enough votes to pass the measure by a simple majority.

Absent further parliamentary gamesmanship, Republicans are expected to seek a ballot on the Medicare measure later.

Another proposal to provide tens of billions of dollars to the U.S. energy industry remains a handful of votes away from passage by the Senate and should be voted on Tuesday. President Bush was said to be busy pressing for support for the two legislative centerpieces of his administration.

Democrats had grown uneasy over the Medicare bill, which would earmark $400 billion over 10 years to subsidize prescription drug purchases by seniors and add more provider options to the main U.S. health insurance entitlement. After passing the House over the weekend, opponents led by Sen. Edward Kennedy (D., Mass.) threatened to block the bill via a filibuster in the Senate Monday.

Pundits remain uncertain about the fate of President Bush's prized energy bill, which in addition to providing the industry with billions in modernization subsidies would revamp the power grid whose failure led to the country's biggest-ever blackout in August. A number of Democrats want the bill held up because of a provision that would indemnify makers of a controversial fuel additive from liability in water contamination.

The energy bill passed the House last week. It takes 60 votes in the Senate to break a filibuster.