Updated at 10:30 a.m. ET
President Barack Obama's health care overhaul easily cleared its second 60-vote test in the Senate early Tuesday morning.
Senate Democrats remained united in their goal of passing the legislation by Christmas, and Republicans were steadfast in opposition.
Tuesday's critical vote involved a procedural move - a motion to shut off debate on a package put together by Senate Majority Leader Harry Reid. It passed 60-39.
The final 60-vote hurdle, which would end debate on the bill itself, is expected Wednesday afternoon, starting a 30-hour countdown to a night-before-Christmas vote on the bill, which needs only a simple majority to pass.
CBS News correspondent Kimberly Dozier reports there's a mandatory waiting time between the votes, pushing the schedule right up to the evening of Christmas Eve. But essentially, it becomes an exercise in calling attendance - as long as all 60 senators in the Democratic voting block show up, and keep saying "aye".
Still, the final outcome remains unpredictable because the Senate measure must be reconciled with a starkly different and more liberal bill already passed by the House of Representatives. That is likely the most difficult step before Obama can sign the legislation into law.
The 10-year, nearly $1 trillion plan before the Senate would extend coverage to some 30 million uninsured Americans, with a new requirement for almost everyone to purchase insurance. Subsidies would be provided to help lower-income people do so, and businesses would be encouraged to cover their employees through a combination of tax breaks and penalties.
Unpopular insurance company practices such as denying coverage to people with existing health conditions would be banned. Uninsured or self-employed Americans would have a new way to buy health insurance, via marketplaces called exchanges where private insurers would sell health plans required to meet certain minimum standards.
The Senate has been voting at odd hours since Monday because Republicans have insisted on using all the time allowed them under Senate rules to delay the bill. Not to be thwarted, Reid has refused to postpone action until after the holidays. Hence the unusual schedule.
On Tuesday, they started voting at sunrise.
With long hours getting in the way of family obligations, frustration has been mounting in the Senate. As the schedule stands, a vote on final passage would not come until late Christmas Eve day.
Reid appealed to senators Tuesday to set aside acrimony and personal rancor and reach for some holiday spirit.
"I would hope everybody will keep in mind that this is a time when we reflect on peace and good things," he said. If Republicans agree, the schedule could be shortened and senators would go home earlier.
The legislation will make a "tremendous difference for families, for seniors, for businesses and for the country as a whole," Obama said Monday.
Democrats prevailed 60-40 over Republican opposition on the first test early Monday, voting to block a threatened Republican effort to try to sink a last-minute package of Democratic amendments.
Republicans vowed to fight on.
"I am willing to stay here. The flight that I have is Christmas morning, and I don't plan on changing that reservation," Sen. Bob Corker told reporters after a meeting of Republican senators. "We potentially are getting ready to pass a bill that there's no question in my mind is going to lead to huge deficits down the road."
Meanwhile, Republican Senator Lindsey Graham said on Tuesday morning that the deals Democratic leaders have cut to round up the votes they need to push the measure through the Senate have been "sleazy."
Speaking Tuesday on NBC's "Today" show, the South Carolina senator cited concessions won by Nebraska Democratic Sen. Ben Nelson, whose support gave Democrats the 60th and final vote they need. Among other things, Nelson won an agreement that the federal government will pay to expand Medicaid services in Nebraska.
Said Graham: "That's not change you can believe in. That's sleazy."
Democratic Sen. Tom Harkin of Iowa defended the concessions on CBS' "The Early Show," saying: "The one that's being talked about for Nebraska, it also benefits other states. It's not just Nebraska."
He also said he would vote for the package even if it didn't contain concessions for Iowa. "The principle of this bill overrides everything," Harkin said. (Watch the Interview with Tom Harkin here)
More on Health Care:
Senate's Deal: Compromise or Corruption?
Tallying the Health Care Bill's Giveaways
What's Next for the Health Care Bill?
Comparison of Senate, House Health Care Bills
Obama: Health Care Vote a "Big Victory"
Some Seek to Kill the 60-Vote Filibuster
Unplugged: Stupak Opposes Senate Abortion Compromise
CBSNews.com Special Report: Health Care