MINNEAPOLIS, Sept. 12 -- Recapturing the energy of his brightest days on the campaign trail, President Obama attempted Saturday to pull his signature health-care initiative out of the summer doldrums with a plea for help from thousands of his most dedicated supporters.

"This is the hard part. This is when the special interests and the insurance companies and the folks who want to kill reform fight back with everything they've got," he told a cheering crowd at the Target Center here. "This is when they spread all kinds of rumors to scare and intimidate the American people. This is what they always do. That's why I need your help."

With his sleeves rolled up and without a tie, Obama used the spirited rally to move into what strategists optimistically call the "closing chapter" in his quest for sweeping changes to the nation's health-care system.

"We're now in the phase where we have to close the deal," Anita Dunn, the White House communications director, said in an interview. The push to sell the public on the proposed changes continues Thursday with a large rally in College Park.

Though the speech here was substantively the same as the one he delivered to a joint session of Congress on Wednesday, the difference in setting and enthusiasm could not have been starker. Obama, who often speaks in professorial tones to explain his health-care plan, adoptted a preacher's cadence Saturday.

Slowly, he unspooled the oft-told story of the petite lady in the "church hat" in Greenwood, S.C., who first uttered what would become his presidential campaign's rallying cry: "Fired up! Ready to go!"

The story, he said, proved "how one voice can change a room.

"If it changes a room, it can change a city," he continued. "If it can change a city, it can change a state.

"And if it can change a state, it can change a nation," he said, reaching a crescendo. "It can bring health care to every American."

"They can't stop us!" he bellowed.

After the "drift" of August, Obama is attempting to "turn hope into success," said informal adviser John Podesta. In the coming weeks, the president and the extensive resources he commands will be used to lavish attention on two groups: Democratic lawmakers and middle-class Americans who are anxious about how the cost of extending coverage to tens of millions of the uninsured will affect their own health insurance and finances.

"You have assets you can deploy to make the case and bump up individual members" of Congress, said Podesta, who served as President Bill Clinton's chief of staff and is head of the Center for American Progress, a progressive think tank.

Already, Vice President Biden, who spent 36 years in the Senate, has stepped up his involvement, meeting with many of his former colleagues. Cabinet members are hitting the road and giving interviews in targeted media markets. Agriculture Secretary Tom Vilsack, for example, is making the rounds of rural radio stations, while Labor Secretary Hilda L. Solis is appearing on Spanish-language television.

As negotiations on Capitol Hill intensify, Podesta said senior White House advisers would begin entertaining more specific requests from lawmakers -- for a presidential visit to the district, for example, or a particular change in a federal health regulation.

At the heart of the strategy is a message to millions of insured-but-anxious middle-class Americans that one of the most popular features of Obama's proposed package -- underwriting reforms -- would be felt immediately, Dunn said.

Under the legislation, insurers would be prohibited from onerous practices such as denying coverage to people with preexisting conditions, placing annual or lifetime caps on coverage and imposing unlimited out-of-pocket fees.

Although many elements of reform would take months or years to implement, the insurance changes could take effect "the day after" a law is signed, Dunn said. Members of Congress "will be able to make the case to constituents that this will have an immediate and real impact on people's lives," she said.

As the president put it: "What this plan will do is to make the insurance you have work better for you."

Even as he hits the road to sell his plan, Obama will continue to intensify his outreach to lawmakers, though Dunn conceded that the prospects for broad bipartisan support have dimmed significantly.

"He will speak to everybody, but he is realistic about the fact that not everyone agrees with him," she said.

Senate Minority Leader Mitch McConnell issued a statement in anticipation of the president's rally, warning that the Obama proposal was too costly and would undermine Medicare.

"The problem isn't the administration's sales pitch," McConnell (R-Ky.) said. "The problem is what they're selling."

Even as the president was speaking here, tens of thousands of people gathered outside the U.S. Capitol in Washington to protest what they called the expansion of the federal government, including Obama's health-care plan.

Increasingly, the White House is reaching out to one GOP lawmaker -- Sen. Olympia J. Snowe (Maine) -- and a bloc of centrist Democrats who have expressed reservations about several elements of the Obama proposal.

In a meeting with some Democratic senators on Thursday, Obama urged them to "focus on the ends, not the means," said Sen. Evan Bayh (D-Ind.).

Part of the challenge, said Bayh, is addressing the "cognitive dissonance" of a $900 billion bill that purports to save money. The senator said he thinks it is possible to achieve that feat -- through dramatic changes in how health care is delivered and paid for. But he acknowledged that the argument "seems incongruous" to lawmakers and average Americans.

For his part, Obama reiterated his pledge that the legislation will pay for expanded coverage largely through savings within the health system and "will not add one dime to the deficit."

The gathering in the Target Center was a reunion of sorts for Obama, who filled the same downtown arena during the presidential primary campaign last year. More than 15,000 people turned out Saturday to see the man they helped elect.

After months of keeping a safe distance from the legislative wrangling, Obama said he is staking his political future on the outcome of the debate.

"I intend to be president for a while, and once this bill passes, I own it," he said in an interview with CBS scheduled to air on "60 Minutes" Sunday night. "I'm the one who's going to be held responsible. So I have every incentive to get this right."