WASHINGTON -- President Barack Obama strongly signaled that Democrats will move forward on a health care overhaul with or without Republicans, preparing his party for a fight whose political outcome will rest with voters in November.

Delivering his closing argument at a 7-1/2-hour televised policy marathon Thursday, Obama told Republicans he welcomes their ideas -- even ones Democrats don't like -- but they must fit into his framework for a broad health care remake that would cover tens of millions of uninsured Americans.

That's the deal.

It's a gamble for Obama and his party, and it's far from certain that Democratic congressional leaders can rally their members to muscle a bill through on their own. At stake are Democrats' political fortunes in the midterm elections and the fate of Obama's domestic agenda pitted against emboldened Republicans.

"The truth of the matter is that politically speaking, there may not be any reason for Republicans to want to do anything," Obama said, summing up. "I don't need a poll to know that most Republican voters are opposed to this bill and might be opposed to the kind of compromise we could craft.

Senate Minority Leader McConnell, House Minority Leader Boehner, Sen. McCain, and Senate Minority Whip Kyl arrive at the Blair House.

"And if we can't," he added, "I think we've got to go ahead and some make decisions, and then that's what elections are for. "

To the nearly 40 lawmakers in the room with him, the message was unmistakable.

"Frankly, I was discouraged by the outcome," said Senate Republican Leader Mitch McConnell of Kentucky. "I do not believe there will be any Republican support for this 2,700-page bill."

Democratic leaders -- who preside over majorities in both chambers-- were having none of that.

"It's time to do something, and we're going to do it," said Senate Majority Leader Harry Reid of Nevada.

Still, no participant publicly called the daylong exercise a waste of time. Despite flare-ups now and then, they had a remarkably civil debate on an issue that has divided Americans and polarized political partisans.

Obama's plan would require most Americans to get health insurance, while providing subsidies for many in the form of a new tax credit. It would set up a competitive insurance market for small businesses and people buying coverage on their own. Other changes include addressing a coverage gap in the Medicare prescription benefit and setting up a new long-term-care insurance program. The plan would be funded through Medicare cuts and tax increases.

At the summit, there were some areas of agreement, including barring insurers from dropping policyholders who become sick, ending annual and lifetime monetary limits on health insurance benefits and letting young adults stay on their parents' health policies into their mid-20s or so.

Sen. Ron Wyden, D-Ore., who has a track record of working across the political aisle, said he would try to broaden common ground. Obama said he was willing to incorporate medical malpractice changes into his plan.

Yet on the core issues of how to expand coverage and pay for it, the divide was as wide as ever. Democrats argue a stronger government role is essential, and with it higher taxes and new rules for private companies.

"We have a very difficult gap to bridge here," said Rep. Eric Cantor of Virginia, the No. 2 House Republican. "We just can't afford this. That's the ultimate problem."

A Democrats-only strategy is no slam-dunk. The House would have to pass a Senate bill that many House Democrats find unacceptable. Indeed, House Democrats appear to hold the key to the success of Obama's gambit.

To make the Senate bill more palatable to the House, both chambers would pass a package of changes. In the Senate, that would be done under special budget rules allowing majority Democrats to get around the requirement for 60 votes to shut off bill-killing filibusters. Democrats are one vote shy.

Sen. Lamar Alexander, R-Tenn., asked Democrats to swear off the tactic, known as "reconciliation." Reid defended it.

Obama said Americans want a decision on health care, and most think "a majority vote makes sense."

Yet a USA Today/Gallup survey released Thursday found Americans tilt 49-42 percent against Congress passing a health care bill similar to the ones proposed by Obama and Democrats in the House and Senate. Opposition was even stronger to the idea of Senate Democrats using the special budget rules, with 52 percent opposed and 39 percent in favor.

Congressional aides said top Democrats will take a few days to gauge the summit's impact on the public and, perhaps more importantly, on moderate House members who will likely determine whether any health care bill will pass.

If the effort fails, Democrats may try a scaled-back plan to insure about 15 million more Americans, rather than the 30 million covered under the congressional bills. Among other things, the fallback plan would require insurance companies to let people up to age 26 stay on their parents' health plans.