President Obama is working on health care legislation intended to reconcile differences between House and Senate Democrats that could be attached to a budget bill and avoid a Republican filibuster, according to a published report.

The president's proposal, which is still being written, will be posted on the Internet by Monday morning, senior administration officials and Congressional aides told the New York Times.

By piggybacking the legislation onto a budget bill, Democrats would be able to advance the bill with a simple majority of just 51 votes, averting a Republican filibuster in the Senate.

The White House signaled Thursday that an aggressive, all-Democratic strategy for overhauling the nation's health system remains a serious option, even as Obama invites Republicans to next week's televised summit to seek possible compromises.

"It will be a reconciliation bill," the Times quoted a Democratic aide as saying. "If Republicans don't come with any substantial offers, this is what we would do."

The administration's stance could set the stage for a political showdown, with Democrats struggling to enact the president's top domestic priority and Republicans trying to block what many conservatives see as government overreach.

Obama's plan, like the House and Senate bills, would expand coverage to some 30 million, require most Americans to carry insurance or face financial penalties, and block insurers from denying coverage to people with pre-existing medical conditions, the Times reported.

One Capitol Hill Democrat told the Times abortion remains "a wild card."

Health and Human Services Secretary Kathleen Sebelius said Thursday that Obama plans to have a health proposal that "will take some of the best ideas and put them into a framework" ahead of the Feb. 25 summit.

Obama has said he is open to Republican ideas for changing the health care system. But many Democrats seriously doubt GOP leaders will support compromises that could draw enough lawmakers from both parties to create a bipartisan majority.

If next week's meeting does not break the logjam, congressional Democrats will face a tough choice. They can pass a highly diluted health care bill or nothing at all, which would send them into the November elections with a high-profile failure despite their control of Congress and the White House.

Or they can use the aggressive and contentious tactic, known as reconciliation, to pass a far-reaching health care bill in the Senate without having to face the GOP. Democrats lost their ability to block filibusters when Massachusetts Republican Scott Brown won a Senate seat last month.

Both parties have used reconciliation rules in the past. But Republicans have practically dared Democrats to do so on health care, citing polls showing significant opposition to the legislation.

It's unclear whether the House or Senate can muster the necessary votes. Democrats, who now hold 255 of the House's 435 seats, drew only one GOP ally when the House passed its health care bill, 220-215, last November. Since then, one Democrat who voted for the bill has resigned, one has died and a third plans to leave office Feb. 28. Moreover, changes meant to meet Senate demands could peel away enough liberals on one end, and party centrists on the other, to cause the revised bill to fail.

In the Senate, Democrats control 59 seats, and reconciliation rules require only a simple majority. But several Democratic senators have expressed discomfort or outright opposition to using the rules to thwart filibusters on health care.

The White House has invited Republicans to bring their own proposals, but GOP leaders have treated the event warily at best.

House Republican leader John Boehner of Ohio said Thursday, "a productive, bipartisan conversation on health care starts with a clean sheet of paper." His office labeled next week's meeting the "summit of all fears."

But at least one moderate Republican was optimistic about the session.

Sen. Susan Collins of Maine said if the summit succeeds, a bipartisan bill could be put together and passed within six weeks. "My advice to our Republican leadership is we should view this as a good faith effort and go in there with a consensus list of provisions that we could support and that would make a difference," she said in an interview with The Associated Press.

House Democrats are insisting on several changes to the bill the Senate passed on Christmas Eve, before Brown was elected to succeed the late Sen. Edward M. Kennedy. The changes include reducing or eliminating a proposed tax on generous employer-provider health plans, and eliminating a Medicaid subsidy aimed only at Nebraska.

Also, some House Democrats who oppose legalized abortion are demanding that the Senate's more permissive language on the topic be replaced by the House provisions. It was unclear Thursday how that might be achieved.

The cost of the legislation -- about $1 trillion over 10 years -- would be paid for through Medicare cuts and a series of tax increases. House officials said Democratic leaders are not yet pressing wary colleagues to back a health care bill under the special procedural rules. That could happen soon, however, if next week's summit fails to produce a bipartisan breakthrough.

House congressional aides said they expect leaders such as Speaker Nancy Pelosi, D-Calif., to tell colleagues that using all their parliamentary muscle to pass a health care bill -- even if it triggers withering criticism from the right -- is preferable to facing voters empty-handed this fall.

The Associated Press contributed to this report.