Obama himself, rallying support outside Washington for the second time this week, , "The time for talk is over. It's time to vote."
At the Capitol, House Speaker Nancy Pelosi said that after days of secretive talks, key Democrats were "pretty close" to accord on additional subsidies to help lower-income families purchase insurance, more aid for states under the Medicaid program for low-income Americans and additional help for seniors who face a coverage gap under current Medicare drug plans.
CBSNews.com Special Report: Health Care
Pelosi, D-Calif., offered no details, and other officials cautioned that any final deal would hinge on cost estimates under preparation at the Congressional Budget Office.
Several officials in both houses also said Democrats were likely to impose a new payroll tax of as much as 2.9 percent on investment and dividend income earned by wealthy taxpayers. In addition, any legislation is expected to include a tax on high-cost insurance plans, along the lines of an agreement the White House negotiated late last year with organized labor.
At stake is the fate of Obama's call to expand health care to some 30 million people who lack insurance and to ban insurance company practices such as denial of coverage on the basis of pre-existing medical conditions. He also hopes to begin to reduce the rise in the cost of health care nationally.
Almost every American would be affected by the legislation, which would change the ways people receive and pay for health care, from the most routine checkup to the most expensive, lifesaving treatment.
Pelosi made her comments as Obama followed his campaign-reminiscent Pennsylvania trip of Monday with an appearance near St. Louis, pushing hard in the home stretch of the marathon battle to pass his signature domestic legislation.
"The time for talk is over. It's time to vote. It's time to vote. Tired of talking about it," he told the crowd.
With his shirt sleeves rolled up, Obama denounced waste and inefficiency in the government's health care system, and he announced that he had signed an executive order directing Cabinet secretaries and agency heads to intensify their use of private auditors to root out fraud.
House and Senate Democrats are working on a complex rescue mission for the health care legislation that appeared on the cusp of passage late last year, before Senate Republicans gained the strength to sustain a filibuster that could prevent final passage.
The current hope of the White House and Democratic leaders is for the House to approve the Senate-passed bill from late last year, despite serious objections to numerous provisions. Both houses would then pass a second bill immediately, making changes in the first measure before both could take effect. The second bill would be debated under rules that bar a filibuster, meaning it could clear by majority vote and without Democrats needing to amass a 60-vote supermajority that is beyond their reach.
Republicans have vowed to do everything they can to thwart the plan, and to go after Democratic supporters in next fall's midterm elections. In the Senate, the GOP rank and file issued a letter pledging to strip out any provision that does not adhere scrupulously to complex rules.
In addition, GOP leaders sought to stoke the fears of House Democrats who worried that the Senate would not approve the second bill. Even so, Sen. Jon Kyl, R-Ariz., the second ranking Senate GOP leader, conceded, "We can't delay a bill for months. We might delay it for a few hours."
Congressional Democrats and the White House are grappling with other issues as they maneuver toward a final vote.
Pelosi and other House Democrats want to include Obama's proposed overhaul of the nation's student loan programs in the second, fix-it health care bill. The measure would require the Department of Education to originate all student assistance loans, effectively eliminating a role for banks and private lenders.
That idea has run into opposition from several Senate Democrats, and while officials said the controversy was debated at length in a closed-door meeting Tuesday night, no decision was made.
Additionally, some House Democrats are hoping to avoid a straightforward vote on the Senate-passed health care bill. Instead, they want a procedural vote that would simply declare the measure to have passed at the moment the Senate cleared the fix-it bill.
Rep. Louise Slaughter, D-N.Y., chairwoman of the House Rules Committee, said that approach was under discussion. But other officials said no decisions had been made.
To the annoyance of some Democrats, the White House is pushing for a vote by the House before Obama leaves on a foreign trip at the end of next week.
Several officials said one of the thorniest issues to be resolved in the House-Senate negotiations was a demand from a dozen states for additional funds under Medicaid.
These states, New York, Pennsylvania and Massachusetts among them, already provide coverage under the low-income program for the poor that other states do not but would be required to if the legislation passes. The 12 are concerned that they will effectively be penalized for having been more generous than the rest of the country.
The legislation that passed the Senate late last year included a new Medicare payroll tax of 2.3 percent on wages for upper-income Americans. The White House wants to extend the tax to dividends and interest, at a higher rate of 2.9 percent.
Much of the proceeds would offset changes in an excise tax the Senate approved on high-cost insurance plans. Responding to criticism from labor leaders, the White House agreed over the winter to scale it back significantly. Officials said the revised proposal would raise about $120 billion less over a decade than the measure the Senate passed.