WASHINGTON - Even the most hardened partisans agree: Republicans and Democrats must find common ground on overhauling America's health-care system or the effort is likely to fail.

"I don't think there's an ounce of disagreement about the principles," said Sen. Christopher Dodd (D., Conn.). "That's unique."

But there is one huge obstacle: Republicans think that the solutions must be found in a more competitive private marketplace, and Democrats prefer that the government ensures that consumers can get coverage. Finding common ground is going to be tough.

A group of elder statesmen launched a major effort yesterday to push both sides toward the middle. Former Senate leaders Bob Dole (R., Kan.), Howard Baker (R., Tenn.) and Tom Daschle (D., S.D.) unveiled a plan that would require individuals and large employers to buy health insurance, create public insurance pools operated by states, and tax some employer-provided health-insurance premiums.

At the White House, spokesman Robert Gibbs praised the proposal. "With this report," he said, "they have demonstrated what can be achieved with bipartisan effort."

But conflicting partisan signals flared from Capitol Hill. Republican and Democratic leaders laid out very different health plans reflecting very different philosophies.

Republican leaders in the House introduced their plan by saying that "Americans who like their health-care coverage [can] keep it," and any plan must "ensure that medical decisions are made by patients and their doctors, not government bureaucrats."

They would provide tax breaks for people who buy insurance on their own and "substantial financial assistance" to low- and moderate-income Americans. Small businesses would be able to band together, with the help of states, other businesses, or trade associations to offer coverage.

All that would be aimed at making the marketplace more competitive, driving down costs for consumers.

In the Senate, the Health, Education, Labor and Pensions Committee was starting to write its own legislation. That plan would cost taxpayers about $1 trillion over 10 years, according to the nonpartisan Congressional Budget Office, and Sen. John McCain (R., Ariz.) immediately protested. "How can we possibly, reasonably address this bill without accounting how to pay for it?" he asked.

Dodd, leading the committee in the absence of the chairman, Edward M. Kennedy (D., Mass.), who is battling brain cancer, assured McCain that the funding would be provided.

But that funding will largely be up to the Senate Finance Committee. That panel had been expected to write its legislation next week but yesterday postponed any action until next month.

The health committee's bill would make people earning about $110,000 for a family of four, eligible for government help with insurance premiums. That figure is expected to drop to about $66,000, when the Finance Committee writes its version of the bill.

The Democratic bill triggered Republican outrage. "Once again, it's rush and spend, and rush and spend, and a tidal wave of debt," said Senate Republican leader Mitch McConnell of Kentucky.

Majority Leader Harry Reid (D., Nev.) fired back: "In fact, 'no' is all we hear from Republicans these days."

The former Senate leaders yesterday gave today's lawmakers a push to pass a bill this year because, if it isn't done this year, electoral politics may block chances of passage for years to come. "So let's do it now," Dole said.