The US Senate has unanimously backed a $US2 trillion ($A3.34 trillion) bill to help unemployed workers and industries hurt by the coronavirus epidemic, as well as providing billions of dollars to buy urgently needed medical equipment.
After bitter negotiations, the deeply divided Senate came together and passed the bill by a 96-0 vote, which sent the massive stimulus package to the House of Representatives for a vote on Friday.
President Donald Trump, whose top aides helped negotiate the bipartisan measure, promised to sign it into law as soon as it reaches his desk. "I will sign it immediately," Trump told reporters on Wednesday.
The rescue package - which would be the biggest ever passed by Congress - includes a $US500 billion fund to help hard-hit industries and a comparable amount for direct payments of up to $US3000 apiece to millions of US families.
The legislation will also provide $US350 billion for small-business loans, $US250 billion for expanded unemployment aid and at least $US100 billion for hospitals and related health systems.
The package is intended to flood the economy with cash in a bid to stem the impact of an intensifying epidemic that has killed more than 900 people in the United States and infected at least 60,000.
Only two other nations, China and Italy, have more coronavirus cases and the World Health Organisation has warned the US looks set to become the epicentre of the coronavirus pandemic.
Top aides to Trump and senior senators from both parties announced they had agreed on the stimulus bill in the early hours of Wednesday after five days of talks.
But it was delayed by criticism from both the right and left on Wednesday, pushing the final vote on passage almost another full day.
Several Republican senators had insisted the bill needed to be changed to ensure that laid-off workers would not be paid more in unemployment benefits than they earned on the job. However, an amendment that would have changed the unemployment provision failed just before the Senate approved the measure.
There had been criticism of the bill from the most progressive wing of the Democratic-led House. Representative Alexandria Ocasio-Cortez called it "a historic corporate giveaway" on Twitter.
However, House leaders hoped the bill would pass by voice vote on Friday, without representatives having to return to Washington. Bringing more than 400 lawmakers from as far away as Hawaii and Alaska would be difficult because a few are in self-quarantine and several states have issued stay-at-home orders.
House Speaker Nancy Pelosi said she hoped the bill would pass quickly, and that Congress would pass further legislation if necessary to ease the crisis going forward.
New York Governor Andrew Cuomo had criticised the bill, saying the $US3.8 billion allocated to his state would not cover tax revenue it will lose from reduced economic activity. New York accounts for roughly half of all US coronavirus cases.
Investors were cheered by the news of the deal. On Wall Street, the benchmark S&P 500 rallied for a second straight day, closing up 1.15 per cent.