The only influence on American politics to match the magnitude of the economic crisis might be the scale of ambition pulsing through President Barack Obama's administration.

An energetic Obama, reasoning that desperate times require daring measures, is refusing to compromise his goal of forging profound political change despite plunging stock markets, wobbling banks and global contagion.

The president, in less than seven weeks in office, is implementing "big policies in a big way," said Tom Baldino, a political scientist at Wilkes University, Pennsylvania.

"It is very clear he is doing everything in his power and marshalling all the resources to demonstrate that what he is doing is a major break from the past," Baldino said.

Obama has embarked on the deepest government intervention in the economy for decades and is arguing the crisis should spur rather than block reform.

He has set about changing how Americans power their homes, the kind of cars they drive and how they get medical treatment and overturned a sheaf of Bush administration policies on issues as diverse as torture and endangered species.

Obama has put a 2010 end date on the Iraq war, sent thousands more troops into Afghanistan and even set his sights on the earth's climate, by vowing to throw the might of the United States into the fight against global warming.

He has committed a total of more than a trillion dollars to shore up the reeling finance industry and to try to wake the comatose economy.

But despite the spending, he is also promising to cut the soaring budget deficit in half by the end of his mandate in 2013 -- though critics say this is based on overly rosy economic forecasts.

While it is too early to judge Obama's policies, his all-action approach is working politically, as polls show the president basking in high personal approval ratings despite the national gloom.

In fact, Obama's personal popularity may be insulating him against early political damage.

In a Quinnipiac University Poll last week, 59 percent of Americans approved of the job Obama was doing -- even though majorities suspected neither he nor his government would be able to haul the country out of the economic mire.

"Clearly, being personable and likeable is for a politician and a president a very important thing," said Peter Brown, assistant director of Quinnipiac's polling institute.

"Being a charismatic figure who people like, his manner, his way of being, his common touch goes a long way."

But some commentators have warned Obama's ambition may be getting out of hand and he risks catastrophic defeats by losing focus on key priorities.

The president sought to debunk that notion himself on Thursday while launching an effort to reform healthcare.

"There's been some talk about the notion that maybe we're taking on too much; that we're in the midst of an economic crisis and that the system is overloaded, and so we should put this off for another day," he said.

"There is always a reason not to do it and it strikes me that now is exactly the time for us to deal with this problem.

"The American people are looking for solutions."

While many of Obama's actions so far -- ordering the closure of Guantanamo Bay, formulating a plan to get troops home from Iraq -- were campaign promises, other actions, like a massive plan to mitigate mortgage foreclosures announced several weeks ago, are impromptu responses to unfolding events.

"Events oftentimes force presidents to do things they would never have envisaged when they were running for office," said Andrew Dowdle, a professor of political science at the University of Arkansas.

Candidate Obama likely never thought he would preside over multi-billion-dollar government rescues of crippled financial institutions or ram a 787-billion-dollar stimulus package through Congress.

But it is on such initiatives that his presidency will face its first real test of public approval in the mid-term congressional elections in 2010.

For now, despite the dire economic times, polling suggests the public is ready to give Obama time for his ambitious agenda to work.

Brown said voters realize Obama inherited a crushing list of problems from the Bush administration, so have set a "low bar" for success.

"The key will be the trend. They don't expect him to take the country back to where it was in the boom within two years.

"But history tells us they want progress, and that will be the key indicator."