CLEVELAND - U.S. President Barack Obama continued Thursday his push for a massive overhaul of America's health system, saying Americans need it and must overcome resistance from opponents in Washington.

Obama increasingly is pitching his remarks directly to voters, hoping they will pressure reluctant lawmakers. He travelled to the industrial Midwestern city of Cleveland to make his case before hundreds who packed a suburban high school gym.

"Reform may be coming too soon for some in Washington," Obama said. "But it's not soon enough for the American people."

Democratic Senate Majority Leader Harry Reid, however, suggested that slowing things down may be the wise course for now.

"It's better to have a product based on quality and thoughtfulness rather than try to jam something through," Reid said, delivering the official announcement of the delay. His words were a near-echo of moderate Republicans who support sweeping changes but criticize Obama's rush to act.

The White House announced Obama will meet in the Oval Office Friday with Reid and Democratic Sen. Max Baucus of Montana, is seeking a bipartisan deal while the health committee bill was pushed through by Democrats on a party-line vote.

The United States is the only major industrialized nation that lacks a comprehensive health care plan, and about 50 million of America's 300 million people are without health insurance.

Most Americans with health insurance receive it through their employers, though those who do not or who are unemployed must either buy costly insurance or pay medical bills out of pocket. The elderly and indigent receive coverage from the government.

"There are those who see our failure to address stubborn problems as a sign that our best days are behind us," Obama said before taking audience questions. He said he believes this generation is ready "to defy the skeptics and naysayers."

Obama ratcheted up the rhetoric one day after he made his case at a White House news conference, and likened the bid to overhaul health care to the manned missions to the moon 40 years ago.

"There are those who see our failure to address stubborn problems as a sign that our best days are behind us," Obama said before taking audience questions. "Well, I believe that this generation, like generations past, stands ready to defy the naysayers and the skeptics."

At a fundraising event in Chicago, Obama urged supporters to back his proposed health care changes. He said the opposition "gets on my nerves. It frustrates me that we'd even be suggesting the status quo is the best we can do."

His plan would insure more Americans, partly through government subsidies; provide a government-run option to compete with private insurers; and require large employers to contribute to health coverage one way or another.

He advised people to lobby senators and representatives for health care reform by telling their own personal stories of concern.

Obama said members of Congress need to hear from the people because "frankly, they are hearing from the other side."

The president took a few swipes at Republican critics in his speech Thursday. But his biggest obstacles are fellow Democrats, who control the House of Representatives and Senate and are moving slowly on his call for widespread changes to U.S. health care.

Senate leaders said Thursday they could not meet Obama's deadline for a vote before the August recess. And a key House committee is struggling to placate moderate Democrats worried about the plan's costs.

"That's OK. I just want people to keep on working. Just keep working," Obama said.

Obama tried to allay worries about the proposed changes, saying the current system of rising costs and uneven care is much worse.

"If you already have health insurance, the reform we're proposing will give you more security," Obama said Thursday. "It will keep the insurance companies out of your health care decisions, too, by stopping insurers from cherry-picking who they cover, and holding insurers to higher standards for what they cover."

For all his efforts, which have included public statements each weekday for the past few weeks, Republican lawmakers and other critics sense momentum building against Obama's plan. They particularly cite nonpartisan cost projections that have not predicted the savings the White House promises.

Louisiana Gov. Bobby Jindal, a leading Republican, said on CBS that he "liked a lot of" what Obama said at the White House news conference Wednesday.

"I think he's actually ... his marketing is the best part of this," Jindal added. "You listen to what the president said. He said he does not want to increase the deficit, does not want government control of health care. He wants people to keep their insurance. He wants to crack down on the abuse, the over-utilization. All that's great. The problem is, that's not what's in the House Democrat bill."

Despite the many problems gripping the country, the health care debate has seized the U.S. political debate.

The stakes are huge for Obama, who is putting much of his credibility on the line to gain passage of legislation. At least one Republican said it could prove to be the president's Waterloo if the drive collapses.

But Obama said: "This isn't about me."

The health care debate may have dented Obama's popularity. His approval rating stands at 55 per cent, according to a new Associated Press-GfK poll, down from 64 per cent in late May and early June. Some 50 per cent approve his handling of health care, but 43 per cent disapprove, and that number has risen sharply since April.

It did not help the White House when the nonpartisan Congressional Budget Office said last week that the bills moving through Congress would add to long-term U.S. costs, not reduce them.