WASHINGTON- President Barack Obama is expected to publish his healthcare plan as early as Sunday or Monday, combining features of the two Democratic bills passed by the Senate and House of Representatives, congressional aides and healthcare advocates said on Friday.

The administration's bill will aim to jump-start the stalled healthcare overhaul and comes just days ahead of a planned televised White House summit with congressional Republicans, who are calling on Democrats to scrap the bills and start over with a far less sweeping proposal.

Democrats are struggling to push healthcare legislation over the finish line in the face of sagging public support and solid Republican opposition bolstered by recent election victories in Massachusetts, Virginia and New Jersey.

The legislation the White House will post on its website is expected to reflect common ground negotiated over the past several weeks by House and Senate Democratic leaders.

Those agreements are likely to be combined as a privileged budget reconciliation bill, which only needs a simple 51-vote majority to pass the 100-member Senate instead of the 60-vote supermajority that has become routine in the Senate and gives Republicans power to block the healthcare bill.

I believe that's the path we are going to take, a senior congressional Democratic aide said.

But it is not clear, even to congressional Democrats, what the White House will include in its legislation and whether Obama will try to add proposals aimed at attracting at least some Republican support.

Senate Majority Leader Harry Reid and House Speaker Nancy Pelosi have not signed off on any final agreement, several Democratic aides have said.

We are still waiting for the president to present to Leader Reid and Speaker Pelosi his plan, a Democratic leadership aide told Reuters.

Valerie Jarrett, one of Obama's closest advisers, said the president would post his draft healthcare bill on the Internet in the next couple of days.

The president is going to craft what he thinks is a good bill. It's not going to be a perfect bill but it's going to be a good bill, she said at Harvard University's Kennedy School of Government in Cambridge, Massachusetts.

FACE-OFF WITH REPUBLICANS

A move to use the budget reconciliation process would fuel Republican opposition even as Obama has called for more bipartisanship in the process.

If the president is sincere about moving forward in a bipartisan fashion, he must take the reconciliation process -- which will be used to jam through legislation that a majority of Americans do not want -- off the table, said Representative Eric Cantor, the second-ranking House Republican.

The Obama face-off with Republicans will give Democrats an opportunity to try to sell their plan to the public and explain why a sweeping, comprehensive proposal is needed instead of the go slow, step-by-step approach advocated by Republicans.

At a campaign event on Friday for Reid in Nevada, Obama blasted Republicans for opposing his healthcare overhaul. The Republicans say that they've got a better way of doing it. So, I want them to put it on the table, he said.

We're going to move forward the Democratic proposal -- we hope the Republicans have one too, Obama said. And we'll sit down and let's hammer it out. We'll go section by section. America can't solve our economic problems unless we tackle some of these structural problems.

Healthcare advocacy groups are looking to the White House proposal and next Thursday's summit to shore up public support, and Democratic votes, in the push to get comprehensive legislation to Obama this year.

As soon as the president and (congressional Democratic) leadership are totally together on substance and a strategy, I think the votes will be there, said Ron Pollack, who heads the Families USA healthcare advocacy group.

The administration, congressional Democrats and advocacy groups have been turning up the rhetorical heat on health insurers that have in recent weeks announced huge premium increases against the backdrop of sizable profits and growing numbers of uninsured people.

The premium increases are a powerful reminder that the healthcare problems are not going away, said David Kendall, a senior health policy advisor at centrist think tank Third Way.

(Additional reporting by Patricia Zengerle in Washington and Jim Finkle in Cambridge, Massachusetts)

(Reporting by Donna Smith; editing by Todd Eastham)