WASHINGTON - Republicans are preparing to use Thursday's White House health care summit to sell their own ideas for using the private marketplace to expand coverage and reduce costs, but they remain wary of fumbling away what they believe is an advantage on the issue heading into this year's critical midterm elections.

GOP leaders are acutely aware of the stakes involved in the extraordinary bipartisan gathering. An effective performance could give their party a vital image boost as November approaches. But if the party's delegation stumbles or oversteps, President Obama and congressional Democrats could see the session provide new life to the stalled health care legislation they have been laboring over for a year.

The Republican strategy is twofold: to portray the Obama plan as radical and ruinously expensive, while reassuring a potential TV audience of millions that the GOP takes the health care crisis seriously and is prepared to address it head on.

But Republicans are not prepared to match every Democratic provision with one of their own. "You will not see from us a 2,700-page comprehensive rewrite of one-sixth of our economy," said Senate Minority Leader Mitch McConnell of Kentucky. "We don't think that ought to be done."

Their goal is to present voters with a clear choice between a Democratic approach that seeks to expand the government role in health care, and the Republican aim of finding solutions in the private marketplace. "There'll be no question as to where Republicans stand," said House Minority Whip Rep. Eric Cantor of Virginia.

Senior Republican aides said the GOP delegation to the summit would seek to portray the Obama proposal as a further threat to the record deficit. Republicans also will be prepared to argue that Congress should be focused on job creation rather than health care.

GOP aides said they anticipate that Obama will zero in on potential weaknesses in the Republican plan. For instance, the House Republican bill would not ban insurance companies from denying coverage to people with preexisting conditions. Nor it would it restrict how much insurance companies can raise their rates.

"We're fully aware of the president's skills," said one top GOP congressional aide. "But this is a debate we've been winning for the last eight months."

Republicans have rallied behind a set of long-held conservative ideas, many proposed by President George W. Bush but never enacted. The list has included new rules that would allow people to buy insurance policies across state lines, the expanded use of health savings accounts, funding to encourage state-based coverage innovation, and limits on lawsuits against doctors.

The Congressional Budget Office estimates the House GOP approach would cost $61 billion over the next 10 years, compared with nearly $1 trillion for various Democratic plans. The Republican proposals would cover about 3 million uninsured people, whereas the Democratic bills aim to reach 30 million.

On Tuesday, McConnell and the House Republican leader, Rep. John Boehner of Ohio, made clear that they had extremely low expectations for Thursday.

"We will be at the meeting on Thursday and anxious to participate in the discussion," McConnell said. "But it appears as if the administration has already made up their mind."

The New York Times contributed to this report.