WASHINGTON — US Treasury Secretary Timothy Geithner urged Congress to do more to help the nation's ranks of unemployed Tuesday, as he previewed tax reform plans and defended President Barack Obama's budget.

Stressing the fragile nature of the US recovery -- and dinging the previous Republican administration for helping dig the hole Americans now find themselves in -- Geithner told the Senate finance committee that lawmakers needed to make law.

"While the economy is gaining strength, we still face significant economic challenges. Unemployment, at 8.3 percent, is still far too high," he said.

"There are 13 million Americans looking for work. We have an obligation to them."

Top of his wish list was passage of Obama's 2013 budget.

The White House on Monday rolled out a $3.8 trillion budget that would increase taxes on the wealthy, while steering cash toward job creation in the short term and cutting deficits in the long term.

Republicans have roundly condemned the plan as replete with tax increases and as repeating "failed" efforts to stimulate the economy through spending.

The proposals face little prospect of passing the Republican-controlled House of Representatives with US politics in the grip of election-year sclerosis.

But Geithner appeared eager to fight the good fight.

"I know the conventional wisdom in Washington is that this debate we begin today does not matter because Congress is too divided to legislate in this election year," he said.

"But this debate is a very important debate, it matters because this is a fundamental debate about economic priorities, about how to increase growth and opportunity."

Geithner also hit George W. Bush for bequeathing the administration a legacy of ashes.

"The harm caused by the crisis came on top of a set of deep, preexisting economic difficulties. In the years leading up to the crisis, the average middle-class family saw few gains in income... and the fiscal policies of the the previous administration turned record budget surpluses into substantial deficits."

The Treasury secretary -- who has indicated he will not serve another term even if Obama wins reelection -- also set the stage for what could be the next congressional rumble between the two parties.

Along with the budget, Geithner urged Congress to extend a package of payroll tax cuts and jobless benefits for the long-term unemployed.

Republicans on Monday said they would be willing to extend the payroll tax cut without an extension of unemployment benefits.

Geithner also set up another showdown, announcing the Democratic administration would set out a "framework" for corporate tax reform "next week."

Geithner gave few details of the plan except to say that it would lower tax rates, widen the tax base and aim at "a system that does a better job of improving incentives for creating and building things in the United States."