WASHINGTON — Tensions flared Monday as Washington strained to respond to the worsening coronavirus outbreak, with Congress arguing over a nearly $2 trillion economic rescue package and an impatient President Donald Trump musing openly about letting the 15-day shutdown expire.

As the U.S. braces for an onslaught of sick Americans, and millions are forced indoors to avert a spike that risks overwhelming hospitals, the most ambitious federal intervention in modern times is testing whether Washington can act swiftly to deal with the pandemic on the home front. By evening, there were no further votes set for Monday, as talks pushed into the night.

Treasury Secretary Steven Mnuchin said late Monday that negotiators still hoped to “close it out” as he left Senate Democratic leader Chuck Schumer’s office. Near 9 p.m. EDT, Schumer strode to the Senate floor upbeat over “very good discussions.” He said they would keep working.

“It’s time to get with the program, time to pass historic relief,” said an angry Senate Majority Leader Mitch McConnell earlier in the day as he opened the chamber after a nonstop weekend session that failed to produce a deal. “This is a national emergency.”

Fuming, McConnell warned Democrats — pointedly House Speaker Nancy Pelosi — to quit stalling on “political games,” as he described Democratic efforts to steer more of the aid toward public health and workers.

Trump, who has largely been hands off from the negotiations, weighed in late Monday from the White House briefing room, declaring that Congress should vote “for the Senate bill as written,” dismissing any Democratic proposal.

“It must go quickly,” Trump said. “This is not the time for political agendas.”

The president also sounded a note of frustration about the unprecedented modern-day effort to halt the virus’s march by essentially shutting down public activities in ways that now threaten the U.S. economy.

Even though Trump’s administration recommended Americans curtail activities starting a week ago, the president said: “We cannot let the cure be worse than the problem itself. At the end of the 15-day period, we will make a decision as to which way we want to go.”

“Let’s go to work,” he said. “This country was not built to be shut down. This is not a county that was built for this.”

Trump said that he may soon allow parts of the nation’s economy, in regions less badly hit by the virus, to begin reopening, contradicting the advice of medical and public health experts across the country, if not the globe, to hunker down even more firmly.

Pelosi assailed Trump’s idea and fluctuating response to the crisis.

“He’s a notion-monger, just tossing out things that have no relationship to a well coordinated, science-based, government-wide response to this,” Pelosi said on a health-care conference call. “Thank God for the governors who are taking the lead in their state. Thank God for some of the people in the administration who speak truth to power.”

The White House team led by Mnuchin worked on Capitol Hill for a fourth straight day of talks as negotiators narrowed on a bipartisan accord.

In the nearly empty building, the virus continued to strike close. Republican Sen. Rand Paul of Kentucky, who announced he tested positive for coronavirus, is now among five senators under self-quarantine. Several other lawmakers have cycled in and out of isolation. And the husband of Sen. Amy Klobuchar, D-Minn., is in a hospital with pneumonia after testing positive, she said Monday.

First lady Melania Trump, meanwhile, has tested negative for the coronavirus, Trump said.

With a wary population watching and waiting, Washington labored under the size and scope of a rescue package — larger than the 2008 bank bailout and 2009 recovery act combined.