"Reform may be coming too soon for some in Washington," Obama told hundreds who packed a high school gym in the Shaker Heights suburb of Cleveland. "But it's not soon enough for the American people."
The president took a few swipes at Republican critics. But his biggest obstacles are fellow Democrats who control the House 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.
"We just heard today that, well, we may not be able to get the bill out of the Senate by the end of August, or the beginning of August," Obama said. "That's OK. I just want people to keep on working. Just keep working."
The president said his critics were urging delay so the overhaul would stall and they could avoid politically difficult votes.
"Sometimes, delay in Washington occurs because people don't want to do anything that they think might be controversial," Obama said, citing the challenges lawmakers faced when creating Medicare and Social Security.
He ratcheted up the rhetoric at the town hall forum here, likening the bid to overhaul health care to the manned missions to the moon 40 years ago.
"Going to the moon was controversial. But at some point, if we're going to move this country forward we can't be afraid to change, especially a system that we know is broken. We've got to get it done and we've got to get it done soon."
In response to a question at the town hall-style event, Obama jumped at a chance to tell the people in audience -- and anyone else listening -- how they can help him get a bill to his desk. 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."
"All those folks who are out there saying, 'We can't afford this, this is socialism, this will lead to government-run health care,' all of the folks who are getting ginned up on talk radio, and some of these cable news shows, you know, I have to say, they have an affect on members of Congress."
Obama dismissed criticism that his plan is too big and moving too fast, saying most of the changes would be phased in over several years.
"Now, is it too much? I don't think it's too much," he said. "It's only too much by the standards of Washington politics today."
Starting with a news conference Wednesday night in Washington, Obama increasingly is pitching his remarks directly to American voters, hoping they will pressure reluctant lawmakers.
"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."
His plan would insure more Americans, partly through government subsidies; provide a government-run option to compete with private insurers; require large employers to contribute to health coverage one way or another; and control Medicaid costs by empowering an executive branch agency to set reimbursement rates for doctors and hospitals, subject to a congressional veto.
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.
"What I heard last night was a president that seems somewhat frustrated that people do not understand what this government health care plan is all about," Rep. Eric Cantor of Virginia, the House Republican whip, said Thursday on NBC's "Today" show. "I think people still have a lot of questions about what a (new) health care plan means for them and their families."
The number of Americans who disapprove of the president's health care plan has jumped to 43 percent, compared with 28 percent in April, according to the latest Associated Press-GfK poll. Obama still holds a strong hand, with most Americans favorable to him in general, and half supporting his health care agenda.
But it's the negative trend in polls that worries his supporters, and some want the president to be even more forceful and visible in pushing his top domestic priority.
"He's the great communicator," said Rep. Jim Cooper of Tennessee, a moderate Democrat who wants lower costs but supports the overall thrust of Obama's efforts. "If anybody can explain this, he can."
"The White House needs to assert more authority," said Cooper, who has focused on health care for years. "I'll be relieved when they take over the marketing of this, because Congress has done a terrible job."
It's hard for Obama, or anyone, to succinctly advocate health care changes just now because multiple versions are slowly moving through the House and Senate.
"The case has not been made" for a particular version because the eventual legislation is unclear, said Rep. Artur Davis, D-Ala.