Democrats have missed previous self-imposed deadlines to vote on the legislation, but their leadership feels confident they can finish on Friday, a senior Democratic aide said on Thursday.

Earlier, Biden had lobbied Democrats in the House of Representatives to vote yes on the bill, as the party tries to recover from sobering state election losses.

Democrats want to pass the $US1.75 trillion ($A2.37 trillion) spending bill and a $US1 trillion ($A1.4 trillion) infrastructure measure that has already been approved by the Senate by Thanksgiving later this month. Party leaders said a vote was possible on Thursday night.

A White House official said Biden was calling various House members and urging them to vote yes.

Biden left for Europe last week for a meeting of G20 leaders and a United Nations climate conference without a deal on the legislation. An affirmative vote before the conclusion of the climate conference in Glasgow on November 12 would bolster the credibility of Biden's pledge to cut US greenhouse gas emissions in half by 2030 compared with 2005 levels.

A leading moderate Democrat raised doubts, however, about the odds of quickly passing the Build Back Better bill on Thursday.

"It's going to be difficult" to resolve all the issues needed to pass the bill on Thursday, Democratic Representative Henry Cuellar told reporters.

With a 221-213 majority in the House of Representatives and a united Republican opposition, Democrats need near unanimity to pass legislation.

Cuellar cited objections to possible immigration provisions, the lack of a final report from the Congressional Budget Office, his own concerns about climate language and a general "lack of trust" in leadership by moderates as factors making it unlikely the bills would be approved on Thursday.

Democrats are reeling from a disappointing loss in Virginia this week when a Republican won the governor's office in a state Biden won handily in 2020. The party is eager to show it can move forward on the president's agenda, and fend off Republicans in the 2022 midterm elections when control of the House and Senate will be on the line.

The nonpartisan US Joint Committee on Taxation issued a report scoring the Build Back Better legislation's tax revenue provisions at $US1.48 trillion ($A2 trillion) over the next decade.

House Speaker Nancy Pelosi and Ways and Means Committee Chairman Richard Neal said the committee's analysis did not account for additional revenue from provisions intended to enhance the Internal Revenue Service's tax collection and to lower the cost of prescription drugs for the Medicare healthcare program for the elderly.

"It's an objective view that it is solidly paid for," Pelosi told reporters after a meeting of House Democrats on the legislation.

Moody's Analytics analysts said on Thursday the bills would be fully paid for and add jobs, but that implementing them would take "deft governance."

In a meeting with fellow Democrats on Thursday morning, Pelosi expressed hope for action on both bills this week, a source familiar with her remarks said.

If passed by the House, the social policy legislation would move to the Senate, also narrowly controlled by Democrats, where Majority Leader Chuck Schumer wants to enact it before the November 25 Thanksgiving holiday.

Australian Associated Press