Spurred on by President Barack Obama, US lawmakers on Thursday prepared for final votes by week's end on an unprecedented 789-billion-dollar plan to help Americans through a painful economic crisis.

The House of Representatives planned to vote Friday on the package, envisioned by Obama in 2008 and worked out in hard-fought but speedy talks this week between Democrats and Republicans.

It is time for Congress to act, and I hope they act in a bipartisan fashion, Obama said during a visit to a manufacturing plant run by heavy machinery giant Caterpillar - which recently laid off more than 20,000 people.

Senate aides said lawmakers there could vote as early as Thursday or Friday but warned of a slim chance that passage -- which would be Obama's biggest legislative victory yet -- might slip to Saturday or Sunday.

Democratic House Speaker Nancy Pelosi said the titanic bill will come to the floor tomorrow and called it a major accomplishment for the new president and his allies in the US Congress.

We make many votes in the congress. They're all important. This one is historic and transformational. I look forward to its passage, Pelosi told reporters with Obama's self-imposed February 16 deadline fast approaching.

Supporters said the bill was roughly 35 percent tax cuts and the rest was new government spending.

They promised it would create or save some 3.5 million US jobs and help pull the US economy out of a paralyzing recession.

The president, who campaigned on the plan last year, visited the US Capitol and addressed lawmakers at a ceremony Thursday marking the 200th anniversary of the birthday of his political hero, slain president Abraham Lincoln.

Later he pursued so far elusive support from his Republican foes with a trip to East Peoria, Illinois, and Caterpillar - which has said the stimulus would let it retain some workers it planned to let go.

We've got to get a final version to my desk so that I can sign it, the president said Wednesday, hoping for a big legislative win after his young presidency suffered a series of early setbacks.

Not one House Republican voted for the chamber's 819 billion dollar version of the bill, and just three joined the Democrats' Senate bloc of 58 votes -- enough to get the bill over the 60-vote threshold need to ensure passage.

It was unclear whether the final vote would include many more Republicans, despite Obama's repeated public calls and private entreaties for the minority party to rally to his push for reviving the US economy.

Out gunned Republicans angrily pressed for at least 48 hours delay to review the bill, the text of which had yet to be made public, but Obama's Democratic majorities seemed little inclined to agree and pushed for final votes.

This is not the smart approach. The taxpayers of today and tomorrow will be left to clean up the mess, said Senate Minority Leader Mitch McConnell, who pointed to a forecast one-trillion-dollar federal budget deficit.

Republicans have attacked the bill as bloated with wasteful spending and lacking enough tax cuts, historically their preferred way to goose the economy.

Democrats have shot back that such steps over the eight years of former president George W. Bush only fueled the current crisis.

Supporters of the bill touted expansions in unemployment benefits, health programs for struggling Americans, and help for cash-strapped states facing cuts in services as critical to easing economic pain.

They also highlighted roughly 150 billion to restore US infrastructure, billions more to develop renewable energy, funds for school constructions and other outlays as investments in future US growth.