Washington  - The United States has now pledged as much as 3 trillion dollars to stabilize the economic and financial systems, but the sheer complexity of the crisis means that many details of the country's recovery plans are still uncertain.

The new promises were part of a whirlwind day Tuesday in Washington - a culmination of President Barack Obama's early efforts to restore confidence in both the banking sector and wider economy.

Tuesday saw a series of government actions, legislative hearings and warnings from administration officials that the crisis could last years, despite the massive federal response.

Treasury Secretary Timothy Geithner laid out the broad strokes of an overhauled effort to address the financial crisis - the first set of blueprints offered by the Obama administration.

Geithner said that the federal government planned to inject as much as 2 trillion dollars into the financial system through a combination of government loans and private investments in a bid to revive bank lending to US consumers.

Three key initiatives were announced: a public-private partnership to buy up troubled mortgage-related assets; an expanded Federal Reserve programme to boost lending to consumers; and fresh capital injections to stabilize US banks, which will include a full review or "stress test" of each bank's exposure to to the credit crisis.

The US Senate, meanwhile, approved a separate stimulus package totalling 838 billion dollars, the largest in US history. The House of Representatives passed its own
819-billion-dollar version last month. The two chambers must now agree on a compromise stimulus measure to be voted into law.

Together, the stimulus spending and financial stability plan form the core of Obama's response to what many believe is the worst economic crisis since the Great Depression.

Both plans mark an unprecedented level of government involvement to address an economic downturn. Neither fiscal stimulus or a financial rescue has been tried on such a scale before, but Geithner said he was convinced that it was better to be bold than cautious.

"There is more risk and greater cost in gradualism than there is in aggressive action. We believe that action has to be sustained until recovery is firmly established," Geithner said in unveiling the administration's plans.

Despite Obama's personal popularity, both plans have been met with skepticism by the US public and legislators. The US stock market plunged Tuesday in its worst one-day loss since Obama's inauguration on January 20.

The stimulus plan has already faced stiff resistance since January from Republicans, most of whom argue it will only saddle future generations with massive debt. On Tuesday, Obama's financial rescue plan was added to the mix.

Hours after unveiling the plan, Geithner testified before a skeptical Senate Banking Committee, where many members complained the administration was preparing to spend mountains of money without providing the kind of specifics that financial markets are seeking.

"I have to be honest with you - a lot of questions still remain," said Senator Bob Menendez, a fellow Democrat. "Right now, I don't quite understand what the full plan is."

Geithner promised more details in the weeks and months ahead, and others praised the administration for taking a deliberate approach that would allow time for input from legislators and other experts.

Federal Reserve Chairman Ben Bernanke testified Tuesday to the House Financial Services Committee. He defended the central bank's own unprecedented effort to stabilize the financial sector since a meltdown in October.

Meanwhile, Obama has taken his message on the road, making a campaign-style townhall appearance Tuesday in Fort Myers, Florida, to drive home the urgency of acting immediately.

"We cannot afford to wait. We can't wait and see and hope for the best," he said. "I believe in hope, but I also believe in action." (dpa)