WASHINGTON — Barack Obama opened his presidency by drawing an unflinching portrait of the challenges. Then he set about turning those perils into possibilities.

In a dizzying dash to Wednesday's 100-day mark, Obama made a down payment on the changes he'd promised and delivered a trillion-dollar wallop to wake up the moribund economy. He put the country on track to end one war, reorient another and redefine what it means to be a superpower.

All this with a cool confidence that has made increasing numbers of Americans hopeful that the country may at last be heading in the right direction.

The public couldn't get enough of it, fixating on Team Obama's every move: the arrival of family dog, Bo; the president showing up for work in his shirt-sleeves; the first lady's moxie in baring her arms; Sasha and Malia's swing set; even a visit to the White House by the surviving Grateful Dead. Obama says it is a "weird fishbowl" that he has jumped into.

Not everyone's impressed. For all that went right with the president's liftoff (after that small matter of the flubbed oath of office), Obama's opening moves have fallen short in the eyes of many, and have left others wondering where it all will lead.

Republicans largely stiffed the president on his call for bipartisanship and cast him as a weak leader on the world stage. Liberals groused that he could have done more and wondered whether he's too prone to compromise. Deficit hawks worried that he's blown a gaping a hole in the budget.

Obama himself seems energized.

"The decision-making part of it," he says, "actually comes pretty naturally." As for the critics, Obama says, Washington is "a little bit like 'American Idol' — but everybody is Simon Cowell."

Almost overlooked in all the hoopla is the historic nature of Obama's tenure as the first black president. There's been little time to even think about that issue, which commanded so much attention during the campaign, as Obama has grappled with a seizing economy and has rushed pell-mell to reverse the legacy of eight years of Republican rule.

"You'd be hard put to find another president facing those kinds of challenges who has acted as intelligently and aggressively to meet the challenges head on," said presidential historian Andrew Polsky, a professor at Hunter College in New York. "He hasn't pushed things to the back burner. Of course, whether any of this works is another question, and it's too soon to know that."

Others are less hesitant to draw conclusions.

Ted Sorensen, a former speechwriter for President John F. Kennedy, says Obama "seems likely to be one of the great presidents in our history."

Former House Republican leader Newt Gingrich says Obama's foreign policy moves have been looking "a lot like Jimmy Carter," a one-term president regarded as a weak leader.

Whatever the record so far, it's clear Obama's biggest challenges are still to come. The pledge to overhaul healthcare will make his successful expansion of children's health coverage look like child's play.

While there have been hints the recession may be easing, Obama still needs to stabilize the shaky banking system and get credit flowing again. The clock is ticking on his promise to close the Guantanamo Bay detention center within a year, and each detainee poses his own set of problems. Obama's ability to wind down U.S. operations in Iraq and reshape efforts in Afghanistan hinges in large part on factors beyond his control.

Obama had hoped that his early actions to ban torture and release top-secret details of past interrogation practices would end a "dark and painful chapter in our history." Instead, they have only inflamed passions and sparked new calls for more investigation and prosecution that are likely to be more than a passing distraction.

CHANGE EVERYWHERE

Change has arrived at a head-snapping rate, a product both of the troubled times and the president's ambitious agenda.

There's been the monstrous economic stimulus package that funneled billions into Obama priorities such as health care and renewable energy; a new law to provide 4 million more children with health insurance; another making it easier for workers to sue over discrimination on the job; the easing of Bush-era restraints on stem-cell research; jaw-dropping revelations about past interrogations; plans to put 21,000 more troops in Afghanistan; the White House-orchestrated ouster of General Motors Corp.'s top executive.

In smaller ways, too, evidence of change is everywhere.

Obama was the first president to host a White House seder to mark Passover. His administration set aside tickets to the annual Easter Egg Roll for gay and lesbian parents. He was the first sitting president to do NBC's "Tonight" show. His weekly radio address airs on YouTube.

There have been blunders along the way. It took three nominations for Obama to get his commerce secretary right, two to find a health secretary. Obama apologized after making an off-key joke suggesting that his lame bowling skills made him Special Olympics material.

Through it all, the economy has been Job One.

For a while, the news was only grim and grimmer.

The Dow Jones Industrials average closed at 7,949 on Inauguration Day. By early March, it was closer to 6,500.

Job losses piled up in staggering increments: 598,000 in January, 651,000 in February, 663,000 in March.

Obama went pedal-to-the-metal to throw money at the problem, first with billions of bailout dollars, next with billions of stimulus dollars, then with a proposed budget expected to produce $9.3 trillion in deficits over the next decade.

House Republican leader John Boehner of Ohio calls it "a spending spree the likes of which our nation has never seen," and polls pick up growing concern on that front.

About half of all Americans say they're "very worried" that the rising national debt will hurt their children and grandchildren, according to an AP-GfK poll.

Taxpayers seethed when word surfaced that insurer American International Group Inc., the recipient of billions in bailout money, had paid millions of dollars in bonuses, and it was all Obama could do to keep out in front of the anger and not get flattened by it.

By mid-April, tensions had eased, and the president was pointing to economic "glimmers of hope." The Dow was back in same range as around Inauguration Day.

For all his focus on the economy, Obama also devoted considerable effort to repairing the nation's tarnished image abroad.

He sat down for his first formal TV interview with an Arabic-language station, telling Muslims that "Americans are not your enemy." In Europe, he said America in the past had "shown arrogance and been dismissive, even derisive." He carried the same message to Latin America, entertaining overtures from isolated Cuban President Raul Castro and Venezuela's anti-American president, Hugo Chavez.

Breaking with the unyielding tone of the Bush years, Obama said he was rejecting the notion "that if we showed courtesy or opened up dialogue with governments that had previously been hostile to us, that that somehow would be a sign of weakness."

Republicans said that was naive, calling the president "a timid advocate of freedom at best," in the words of former Republican presidential hopeful Mitt Romney.