WASHINGTON - As President Obama's senior advisers gathered at Blair House at the end of July for a two-day review of their first six months in office, what was meant to be a breath-catching moment of reflection was marked by a sense of unease.

To a sleep-deprived White House staff, the achievements since taking office that chilly Jan. 20 morning seemed self-evident. The agenda of necessity they had carried out to stabilize the economy was rapidly making room for Obama's agenda of choice, changing the way Americans get health care, generate and use energy, and learn in public-school classrooms.

But opinion polls showed support for the president and his policies dipping sharply, and the disheartening numbers had shaken the confidence of some of Obama's staff. Vice President Biden addressed the anxiousness when the cabinet and senior staff met in the State Dining Room in the White House the next morning.

"Did you really think this was going to be easy?" Biden asked, according to one participant.

The slide has only quickened since. Emerging from an angry August recess, Obama is weakened politically and faces growing concern, particularly from within his own party, about his strength as a leader. Dozens of interviews this summer in six states have suggested growing angst and disappointment over the administration's present course.

Democratic officials and foot soldiers, who have experienced the public mood firsthand, want Obama to take a more assertive approach in the fall. His senior advisers say he will, beginning with his address to Congress Wednesday on health care.

His challenge, however, is more fundamental. Obama built his successful candidacy and presidency around a leadership style that seeks consensus. But he is entering a period when consensus may not be possible on the issues most important to his administration and party. Whatever approach he takes is likely to upset some of his most ardent supporters, many of whom are unwilling to compromise at a time when Democrats control the White House and Congress.

"Until last week, he was still trying to play ball with the Republicans who said, 'We're going to bring you down,' " said Karen Davis, 42, a musician from Jersey City, N.J., who raised money for Obama last year. "Now I'm thinking, this isn't what I voted for."

Obama has brought change in his first seven months in office, often through direct government intervention, to matters as varied as the conflict in Iraq and the American auto industry.

The economy is improving and bailed-out banks are paying back the money with interest. A smooth Supreme Court selection has brought the first Hispanic justice, Sonia Sotomayor, to the nation's highest bench. America's standing in the world is improving, according to many polls.

But Obama's spending plans that will require $9 trillion in new borrowing over the next decade have alarmed conservatives in his own party, and he failed to head off an investigation by his own Justice Department into the Bush administration's interrogation policies that he had made clear he did not want. Unemployment is still rising. His decision to expand the war in Afghanistan has not come with a clear plan for how to leave.

Even though polls show fallen approval ratings, Obama remains more personally popular than his policies. His senior advisers say his leadership strength derives from his ability to remain calm in the maelstrom of 24-hour news cycles, a mark of his once-long-shot 2008 campaign. The antigovernment anger that has risen from countless town-hall meetings over the recess is testing Obama's celebrated communication skills and a political style one confidante described as "unsentimental."

"I know there is great value associated in this town with the straight right jab and the occasional knee to the groin," said David Axelrod, a senior Obama adviser. "He'll throw the jab when he sees it, when he feels it's necessary. But he's not likely to throw the knee."

The anxiety stretches from New England to the Pacific Ocean, judging by recent visits, and is rooted in the measures Obama has taken to shore up the economy.

Activist presidents have always spent political capital pursuing their goals. As he told volunteers at a health-care rally last month: "The easiest thing to do as a politician is to do nothing."

Smaller than it was a decade ago, the Republican Party has shed many moderates, leaving few who are willing to work even with a Democratic president who has promised less partisan governing.

Only three Republican senators voted for the stimulus measure, written in large part by congressional leaders but pushed through in the final hours by the White House. One of them - Pennsylvania's Arlen Specter - is now a Democrat. Not a single House Republican voted for it.

Axelrod said the White House had been receiving advice, much of it unsolicited, to push back harder against the opposition, particularly as the health-care debate heads into the fall legislative session. He said the president intended to do so, but on his own terms.

"He's not going to get punked or pushed around," Axelrod said. "On the other hand, I don't think he's going to fill his day with gratuitous partisan back-and-forth, because it isn't productive, and it's not healthy."