Congressional Democrats and President Barack Obama began work in earnest Tuesday on difficult issues still standing in the way of their sweeping health care overhaul after months of tortuous debate. Topping the list: How to help Americans pay for insurance premiums.

The Democratic-controlled White House and Congress are now closer to achieving near—universal health care than any of their predecessors. Extending health care coverage to 30 million out of nearly 50 million uninsured Americans brings the president close to achieving his top domestic priority.

Obama wants to sign legislation to extend insurance coverage by the time of his State of the Union speech, expected in early February. Separate bills passed by the House of Representatives and Senate, which must now be merged, would require nearly all Americans to get coverage and would provide subsidies for many who can’t afford the cost -- but they differ on hundreds of details. Pocketbook concerns join abortion and the federal government’s role in health care as the top issues for negotiators.

The negotiations are the last chance for Democrats to shape the legislation to deliver concrete benefits to Americans sceptical that it will help control skyrocketing premiums as it expands coverage to millions more.

At a White House meeting that stretched into Tuesday evening, the president and Democratic congressional leaders agreed on fast-track negotiations that would bypass the need for a formal conference to resolve differences between the House and Senate health care bills.

Obama met with Democratic House Speaker Nancy Pelosi and House Majority Leader Steny Hoyer at the White House on Tuesday evening. Joining the discussion by telephone were Democratic Senate Majority Leader Harry Reid and Sen. Dick Durbin who were out of town.

House Democratic leaders will head back to the White House on Wednesday afternoon. Staffers from the House and Senate will meet with administration aides this week to formally begin sorting through issues -- with the White House taking a lead role in settling disputes, said a congressional leadership aide, who described the private meeting on condition of anonymity.

Republicans weren’t invited to Tuesday’s talks, and they complained that the Democrats intended to deliberate behind closed doors -- though lawmakers often do so in the final stages of such complex legislation. Separately, the head of C-SPAN, the nonpartisan public affairs network, called for televising the discussions -- as Obama once had promised.

House Democrats face the virtual certainty that they will not get the government-run insurance plan liberals had sought, a point Pelosi acknowledged after meeting earlier in the day with key committee leaders.

In exchange for losing the federal “government option,” House Democrats say they intend to press the Senate to make premiums more affordable for Americans. The outcome of the talks could mean savings of hundreds of dollars for families buying coverage through new insurance supermarkets created by the legislation.

White House officials say the bills have 95 percent in common. Maybe so, but the remaining issues could be hard to resolve in the few weeks Obama has in mind. Among them: whom to tax, how many people to cover, how to restrict taxpayer funding for abortion, whether illegal immigrants should be allowed to buy coverage in the new markets with their own money. The list goes on.

Concerns about affordability are paramount. Major subsidies under the bills won’t start flowing to consumers until 2013 at the earliest. Even with federal aid many families would still face substantial costs.

The House would provide much greater financial help for households making as much as three times the federal poverty level, $32,490 for an individual, $66,150 for a family of four, according to a side—by—side analysis prepared by House Democratic staffers.

There could be common ground in a Senate proposal to raise payroll taxes on individuals making more than $200,000 and married couples over $250,000.