President Donald Trump lashed out at Congress during a coronavirus task force briefing Wednesday, complaining about his nominations not moving forward and threatening unprecedented action towards the branch of government that serves as a powerful check on his presidency.

Noting that the Senate has left Washington until May 4 at the earliest, Trump championed his right to make recess appointments and rejected the use of “pro forma” sessions, during which the chambers of Congress briefly come to order to conduct no real business. The practice allows the House and Senate to maintain flexible schedules without mutually agreeing on adjournment dates.

“The Senate's practice of gaveling in to so called pro forma sessions where no one is even there has prevented me from using the constitutional authority...given under the recess provisions,” Trump said. “The Senate should either fulfill its duty and vote on my nominees or it should formally adjourn so that I can make recess appointments .”

He then targeted the U.S. House, saying if they did “not agree to that adjournment, I will exercise my constitutional authority to adjourn both chambers of Congress.” House Democrats have targeted May 4 as their return date, too.

“The current practice of leaving town while conducting phony pro forma sessions is a dereliction of duty that the American people cannot afford during this crisis,” Trump said. “It is a scam, what they do. It's a scam and everybody knows it. And it's been that way for a long time.”

Trump’s latest attempt to flex his authority comes just days after he touted unfounded authority over states' decisions to re-open during the pandemic. He’s since backed away from the false claim.

While the Constitution grants the president authority to adjourn the House and Senate to a date he prefers if the chambers cannot agree on an adjournment date, this power has never been used in the history of the presidency. Trump’s doing so would be certain to create a crisis of balance of constitutional power between the two branches; he could also be stymied by congressional leadership.

Trump seemed to point to that during the briefing, saying “perhaps it's never done before, it's never been done before. Nobody's even sure if it has. But we're going to do it. We need these people here. We need people for this crisis and we don't want to play anymore political games.”

The last time Trump sought to wield his recess appointment power was in 2017, to replace then-Attorney General Jeff Sessions. The GOP Senate majority kept pro forma sessions in place, though they noted it was not in order to block Trump.

While Trump is seeking confirmation for pending judicial nominations—slots that Senate Majority Leader Mitch McConnell has been eager to fill—in recent weeks he also put forward a slate of fresh nominees for inspector general positions after firing several of the independent watchdogs.

Trump is also seeking confirmations for a Director of National Intelligence and a group of key economic posts, from the Federal Reserve board to U.S. Treasury posts overseeing financial markets.

While Trump tried to tie his grievances to the pandemic, the actual time spent with the medical experts on the task force was incredibly thin Wednesday. Deborah Birx, the task force response coordinator, spoke for less than five minutes during her portion of the briefing.