A spirited and potentially long debate was expected, as most Republicans oppose the cost of the bill that would pay for vaccines and other medical supplies to battle a COVID-19 pandemic that has killed more than 500,000 Americans and thrown millions out of work.

The measure would also send a new round of emergency financial aid to households, small businesses and state and local governments.

A group of Senate Republicans had offered Biden a slimmed-down alternative, but the White House and some economists insist a big package is needed.

Biden has focused his first weeks in office on tackling the greatest public health crisis in a century, which has upended most aspects of American life.

Democrats control the House by a 221-211 margin, and Speaker Nancy Pelosi is counting on nearly all of her rank and file to get the bill passed before sending it to a 50-50 Senate where Democratic Vice President Kamala Harris holds the tie-breaking vote.

Embedded in the House bill is a federal minimum wage increase, which would be the first since 2009 and would gradually bump it up to $US15 an hour in 2025 from the current $US7.25 rate.

But the future of the wage hike was cast into doubt on Thursday, when the Senate parliamentarian ruled that it could not be allowed under the Senate's "reconciliation" rules that govern the massive bill.

The special rules allow the legislation to advance in the Senate with a simple majority of the 100 senators, instead of the 60 needed for most legislation.

The $US15 minimum wage figure had already faced opposition in the Senate from most Republicans and at least two Democrats, which would have been enough to sink the plan. An array of senators are talking about a smaller increase, in the range of $US10 to $US12 per hour.

In a statement after the Senate parliamentarian's ruling, Pelosi said: "House Democrats believe that the minimum wage hike is necessary. Therefore, this provision will remain in the American Rescue Plan on the Floor tomorrow."

In arguing for passage of the relief bill, Pelosi cited opinion polls indicating the support of a significant majority of Americans who have been battered by the year-long pandemic.

"It's about putting vaccinations in the arm, money in the pocket, children in the schools, workers in their jobs," Pelosi told reporters on Thursday.

Among the big-ticket items in the bill are $US1400 direct payments to individuals, a $US400-per-week federal unemployment benefit through August 29 and help for those having difficulties paying their rent and home mortgages during the pandemic.

An array of business interests also have weighed in behind Biden's "America Rescue Plan" Act.

Republicans have criticised the legislation as a "liberal wish-list giveaway" that fails to dedicate enough money to reopening schools that have been partially operating with "virtual" learning during the pandemic.

Australian Associated Press