Marking his symbolic 100th day in office, President Barack Obama has pledged an "unrelenting, unyielding effort" to return to US prosperity and confront threats including swine flu and terrorism.
Early on Wednesday he visited the American heartland, telling a town-hall style event in Missouri that while he was "pleased with our progress ... I am not satisfied" with the accomplishments in his first four months.
And the US leader stressed there was a long slog ahead to pull the nation out of its worst recession since the Great Depression in the 1930s.
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He brought the same message to a national audience during an evening press conference in which he displayed a mastery of policy details, from the upheaval in the US auto industry and legislative bickering on Capitol Hill, to foreign policy touchstones including the need to safeguard Pakistan's nuclear arsenal.
"We still confront threats ranging from terrorism to nuclear proliferation to pandemic flu," Obama stressed.
He immediately highlighted the threat of a swine flu pandemic, and vowed the United States will do "whatever it takes" to control the outbreak which has claimed at least eight lives, one a Mexican toddler who died in Texas.
Obama also defended his 3.4-trillion-dollar budget for 2010 -- approved by the House of Representatives Wednesday and due to be voted on by the Senate later this week -- as a budget which "builds on the steps we've taken over the last 100 days to move this economy from recession to recovery and ultimately to prosperity.
"So we are off to a good start, but it is just a start," he said, warning that more pain lies in store.
"Millions of Americans are still without jobs and homes, and more will be lost before this recession is over.
"All of this means you can expect an unrelenting, unyielding effort from this administration to strengthen our prosperity and our security -- in the second hundred days, and the third hundred days, and all the days after."
In Missouri, Obama said his administration had begun "remaking America" since taking office January 20 by reversing the contentious policies of George W. Bush's administration and orchestrating a historic 787-billion-dollar stimulus bill, among other reforms.
Obama's broad agenda during his debut -- seen as a success by most Americans, according to opinion polls -- is widely considered one of the fullest plates for any new president in decades, and he openly acknowledged he was stunned by the onslaught of crises facing the administration.
"I am surprised ... by the number of critical issues that appear to be coming to a head at the same time," Obama said in a rare moment of exasperation.
"If you could tell me right now that when I walked into this office that the banks were humming, the autos were selling, and that all you had to worry about was Iraq, Afghanistan, North Korea, getting health care passed, figuring out how to deal with energy independence, deal with Iran, and a pandemic flu, I would take that deal."
But in addition to those issues, Obama is tasked with pulling the country out of the steepest economic freefall since the depression.
In an emergency bid to keep Americans from avoiding foreclosures, a 75-billion-dollar fund has been created to help embattled homeowners.
His administration has also intervened to try to help save teetering US auto giants Chrysler and General Motors, and injected billions of dollars into struggling banks and other companies in moves that critics have decried as partial nationalization.
On other domestic fronts, Obama has expanded a state health insurance scheme to cover millions of children, broadened unemployment benefits, and overturned Bush's restrictions on embryonic stem-cell research.
Abroad, Obama has recast US foreign policy by putting greater emphasis on multilateral diplomacy, reaching out to Muslims, and vowing to end decades of enmity with foes Cuba and Iran.
The US president has also made a start on rolling back Bush's "war on terror" policies by mandating the closure of Guantanamo Bay prison camp, outlawing torture and setting a timetable for withdrawal from Iraq.
On Wednesday he stressed that the legal rationale used by his predecessor to justify waterboarding against detainees was a "mistake" and that the simulated drowning tactic is "torture."
Obama has also doubled down in Afghanistan and Pakistan to tackle mounting unrest. On Wednesday he said he was "gravely concerned" about the situation in Pakistan but "confident" the country's nuclear arsenal can be kept out of the hands of Islamist extremists.