By David Morgan and Doina Chiacu

WASHINGTON (Reuters) – U.S. Senate Democrats are prepared to block Republicans from moving forward on a partisan coronavirus aid bill, the chamber’s top Democrat warned on Monday, as Republican leaders were expected to meet at the White House to discuss legislation.

The Republican-controlled Senate and Democratic-led House of Representatives have less than two weeks to hammer out a new relief package before enhanced unemployment benefits run out for tens of millions of American workers made jobless by the COVID-19 pandemic.

Senate Majority Leader Mitch McConnell and House Republican leader Kevin McCarthy were due to discuss legislation with President Donald Trump and Treasury Secretary Steven Mnuchin at the White House on Monday, a White House official said over the weekend.

But Senate Democratic leader Chuck Schumer warned Republicans not to try to move forward on their own legislation, saying Senate and House Democrats would unite to demand bipartisan action.

“We will stand together again if we must,” Schumer said in a letter to colleagues. “A bipartisan, bicameral process will result in a much better bill for the American people.”

Congress has so far passed legislation committing $3 trillion to the crisis. In the more than 12 weeks since Trump signed the last response law, the number of U.S. coronavirus cases has more than tripled to over 3.7 million.

Similar partisan standoffs preceded the last bills.

Senate Republican plans to unveil a coronavirus bill this week have been upstaged by a White House effort to eliminate billions of dollars for coronavirus testing and tracing from the legislation.

“That goes beyond ignorance. It’s just beyond the pale. Hopefully, it was a mistake and they’ll back off it, because it is so very wrong,” House Speaker Nancy Pelosi told MSNBC.

Republicans and Democrats appear to be far apart on what should be included in the next coronavirus package.

Republicans have circulated draft documents laying out liability protections for businesses, schools, government agencies and charities.

Democrats, who oppose liability protections, have pledged to fight for legislation akin to the $3 trillion bill that the House approved in mid-May. McConnell has said his bill would not cost more than $1 trillion.

(Reporting by Doina Chiacu and David Morgan; Editing by Scott Malone and Jonathan Oatis)