WASHINGTON - U.S. Senate Democrats cleared the second of three 60-vote hurdles on President Barack Obama's healthcare overhaul on Tuesday, moving its version of the landmark legislation one step closer to passage before Christmas.

For a second straight day, Democrats mustered 60 party-line votes to cut off debate on the healthcare bill and move toward Senate passage over unanimous Republican opposition.

The last 60-vote hurdle will come on Wednesday, with a vote to approve the bill -- which requires a simple majority in the 100-seat chamber -- scheduled for 8 a.m. EST on Christmas Eve on Thursday.

The finish line is in sight, Democratic Senator Max Baucus, chairman of the Finance Committee, told reporters. Now we know with certainty we have the will to cross it.

The Senate also passed Democratic leader Harry Reid's 383-page amendment making final changes to the measure, including striking a government-run insurance plan and tightening restrictions on using federal funds for abortions.

Those changes helped secure the 60th vote for Democrats on Obama's top legislative priority, which would extend health coverage to more than 30 million uninsured and halt industry practices like refusing insurance to people with pre-existing medical conditions.

The healthcare fight has consumed Congress for months, sparking intense political brawling and resulting in a grueling schedule this week in which senators were summoned for votes after midnight and at daybreak.

There is a lot of tension in the Senate, Reid said after the votes. Let's just all try to get along. Let's try to work through this.

Once passed, the Senate bill must be melded with a version passed by the House of Representatives on November 7 in what promises to be difficult negotiations. Both chambers must approve it again before sending it to Obama for his signature.

TOUGH TALKS

Democrats hope to complete House-Senate negotiations and send the bill to Obama before his State of the Union message in late January, although deadlines for finishing the healthcare package have been missed repeatedly.

But the negotiations face looming clashes on issues like the government-run plan, which is in the House bill but not the Senate, abortion, and competing approaches on how to pay for the changes.

This is not over yet, Republican Senator John Thune said.

Republican critics say the measure is an expensive and heavy-handed intrusion into the healthcare sector that will drive up costs, increase the budget deficit and reduce patients' choices.

The nonpartisan Congressional Budget Office estimated the Senate bill will cut the federal deficit by $132 billion over 10 years, but critics argue the revenue increases and cost savings the bill calls for may never materialize.

Republicans also attacked special deals in the bill for Democratic senators like Ben Nelson, who backed it after winning extra money for his home state of Nebraska, and Chris Dodd, who faces a tough re-election fight in Connecticut and won money for a medical center there.

This bill is a mess, and so was the process that was used to get it over the finish line, Senate Republican leader Mitch McConnell said. Americans are outraged by the last-minute, closed-door, sweetheart deals that were made to gain the slimmest margin for passage.

The loss of even one Democrat would sink the plan in the 100-member Senate. Democrats control 60 votes, the exact number needed to overcome united Republican opposition.

The overhaul would spark the biggest changes in the $2.5 trillion U.S. healthcare system since the 1965 creation of the government-run Medicare health program for the elderly.

The Senate bill would require most Americans to have insurance, give subsidies to help some pay for it, and create state-based exchanges where the uninsured could comparison shop for plans.

Obama said he will delay his planned Hawaiian vacation, scheduled to start on Wednesday, until the bill is passed.

If they're making these sacrifices to provide healthcare to all Americans, then the least I can do is to be around and to provide them any encouragement and last-minute help if necessary, Obama told reporters after a meeting with community bankers at the White House.

Obama has asked the Senate to finish work on the bill before January to try to keep the issue from spilling into the November 2010 congressional election campaigns. Most opinion polls show the bill losing public support, with majorities now opposed to it.

(Editing by Arshad Mohammed, Vicki Allen and Paul Simao)