US Senate Majority Leader Mitch McConnell speaks during a press conference on Capitol Hill in Washington, DC, the United States, November 17. Photo: Xinhua

US lawmakers agreed on a nearly $900 billion COVID-19 relief package for millions of Americans on Sunday, in a deal that follows months of wrangling and comes as the nation battles the world's largest coronavirus outbreak.

The package includes aid for vaccine distribution and logistics, extra jobless benefits of $300 per week, and a new round of $600 stimulus checks - half the amount provided in checks distributed in March under the CARES Act.

Months of partisan debate and finger-pointing, as well as last-minute negotiations, culminated in a deal lawmakers said they hoped to formally approve on Monday.

Talks had taken place amid a highly contentious campaign for the US presidency and Donald Trump's subsequent refusal to concede defeat to Democrat Joe Biden.

"We've agreed to a package of nearly $900 billion. It is packed with targeted policies to help struggling Americans who have already waited too long," Republican Senate majority leader Mitch McConnell said in a statement.

Democratic House Speaker Nancy Pelosi and Senate minority leader Chuck Schumer confirmed an agreement had been reached with Republicans and the White House on a deal that "delivers urgently needed funds to save the lives and livelihoods of the American people as the virus accelerates."

The agreement also contains $25 billion in housing aid to prevent evictions and nearly $100 billion to help schools and childcare facilities reopen, a statement from Pelosi and Schumer said.

Congress was working under a deadline of midnight Sunday, needing to reach consensus to avoid a government shutdown.

Number two House Democrat Steny Hoyer said he expected the deal to pass on Monday and then head to the Senate.

That meant it required passage of a stopgap measure - which was signed by Trump late Sunday - to keep the federal government funded an extra 24 hours and avert a shutdown.

The House and Senate approved the stopgap measure earlier Sunday.

"The House will move swiftly to pass this legislation immediately, so it can quickly be sent to the Senate and then to the president's desk for his signature," Schumer and Pelosi said in a statement. 

"With the horrifying acceleration of daily infections and deaths, there is no time to waste."

In the wake of the deal, president-elect Biden welcomed the agreement but said more will need to be done.