President Donald Trump is threatening to torpedo Congress’ massive COVID-19 relief package in the midst of a raging pandemic and deep economic uncertainty, suddenly demanding changes fellow Republicans have opposed.

Trump assailed the bipartisan $900 billion package in a video he tweeted out Tuesday night and suggested he may not sign the legislation. He called on lawmakers to increase direct payments for most Americans from $600 to $2,000 for individuals and $4,000 for couples.

Railing against a range of provisions in the bill, including for foreign aid, he told lawmakers to “get rid of the wasteful and unnecessary items from this legislation and to send me a suitable bill.”

Trump did not specifically vow to veto the bill, and there may be enough support for legislation in Congress to override him if he does. But if Trump were to upend the sprawling legislation, the consequences would be severe, including no federal aid to struggling Americans and small businesses, and no additional resources to help with vaccine distribution. In addition, because lawmakers linked the pandemic relief bill to an overarching funding measure, the government would shut down on Dec. 29.

The relief package was part of a hard-fought compromise bill that includes $1.4 trillion to fund government agencies through September and contains other end-of-session priorities such as money for cash-starved transit systems, an increase in food stamp benefits and about $4 billion to help other nations provide a COVID-19 vaccine for their people.

Lawmakers spent months in a stalemate over pandemic relief funds, even as COVID-19 cases soared across the country. Democrats had pushed for higher payments to Americans, but compromised with Republicans to allow a deal to proceed.

Following Trump’s interjection, House Speaker Nancy Pelosi all but dared Trump’s Republican allies in Congress to meet the president’s demand for far higher payments.

“At last, the President has agreed to $2,000. Democrats are ready to bring this to the Floor this week by unanimous consent. Let’s do it!,” Pelosi said in a tweet. An aide said she would put the proposal forward Thursday for a vote.

Republicans have been reluctant to spend more on pandemic relief and only agreed to the big year-end package as time dwindled for a final deal. And Sen. Chuck Schumer, the Senate Democratic leader, said that “Trump needs to sign the bill to help people and keep the government open,” and Congress would step up for more aid after.

Trump’s call for changes to the legislation will test his sway with a Republican Party he has held tight control of throughout his presidency. Several Senate Republicans, including Majority Leader Mitch McConnell, have begun to gingerly break with Trump and acknowledge his defeat to President-elect Joe Biden, a step Trump has refused to take. McConnell has also warned Republicans against disputing the election on Jan. 6, when Congress must formally affirm the results.