Majority Leader Mitch McConnell (R-Ky.) and Senate Minority Leader Charles E. Schumer (D-N.Y.) were expected to discuss the breakthrough on the Senate floor shortly, after a long day of talks with Treasury Secretary Steven Mnuchin, Ueland and others.

The agreement capped five straight days of intensive negotiations that occasionally descended into partisan warfare as the nation’s economy reeled from the deadly pandemic, with schools and businesses closed, mass layoffs slamming the workforce, and tens of thousands falling ill.

Other provisions include a massive boost to unemployment insurance, $150 billion for state and local stimulus funds and $130 billion for hospitals, among numerous other provisions.

Tuesday began with all parties predicting a deal would be imminent, along with a vote by Tuesday evening. But as the hours dragged on multiple disputes arose and legislative language required close review.

Finally, as midnight neared Tuesday, the pace of shuttle diplomacy picked up on the second floor of the Capitol, as Mnuchin, Ueland and newly named White House chief of staff Rep. Mark Meadows (R-N.C.) met alternately with McConnell and Schumer, who was in frequent contact with House Speaker Nancy Pelosi (D-Calif.).

The stock market rose sharply Tuesday in anticipation of the deal, with the Dow Jones industrial average surging more than 2,100 points or 11.4 percent. The government is dealing with a number of competing pressures, though, as President Trump declared that he’d like much of the country to be up and running by April 12 even though the number of people testing positive for the novel virus in the U.S. continues to climb.

The Senate bill would direct payments of $1,200 to most American adults and $500 to most children, create a $500 billion lending program for companies, states, and cities, and extend an additional $367 billion to help small companies deal with payroll problems. It would bolster the unemployment insurance system and pump $150 billion into U.S. hospitals. The bill more than doubled in size in just a few days.

White House National Economic Council Director Larry Kudlow called it the “single largest Main Street assistance program in the history of the United States.”

The delay in finalizing a deal came, in part, because aides launched a painstaking scrub of the bill’s text, to make sure that one of the most ambitious pieces of legislation ever attempted by Congress — thrown together in little over a week — actually said what lawmakers wanted it to say.

Senate Republicans were being extra meticulous because they felt an earlier and much smaller coronavirus relief bill, which Mnuchin negotiated in a rush with Pelosi earlier this month, turned out to have provisions related to paid sick leave that GOP senators opposed – but which they reluctantly accepted. Now, they wanted to double- and triple-check Mnuchin’s work in brokering a deal with Schumer given the enormous stakes.

As lawmakers neared a deal, the White House made a significant concession to Democrats’ demands, agreeing to allow enhanced scrutiny over the massive loan program that is a centerpiece of the Senate’s $2 trillion coronavirus economic package.

This pertains to the $500 billion loan and loan guarantee program that the Treasury Department would be tasked with administering for companies, states, and cities. Of that amount, $425 billion is supposed to go to businesses, cities and states. An additional $50 billion would go to passenger airlines, as well as $8 billion for cargo airlines, and $17 billion for firms that are deemed important to national security.

Trump has already said he wants some of the money to go to the cruise ship industry, and he also wants assistance for hotels. When he was asked Monday evening who would perform oversight of the program, Trump responded, “I’ll be the oversight.”

The legislation would also significantly boost unemployment insurance, expanding eligibility and offering workers an additional $600 a week for four months, on top of what state unemployment programs pay.

The legislation also contains $130 billion for hospitals and $150 billion for a state and local stimulus fund, both major Democratic priorities, Schumer told fellow Democrats on a conference call, according to a person familiar with the call who spoke on the condition of anonymity to discuss it.

Lawmakers of both parties are under extreme pressure from their constituents and health-care providers in their districts and states to act to provide desperately needed money and supplies amid widespread shortages and waves of layoffs. As of Tuesday evening, there were more than 55,000 confirmed cases of the coronavirus in the United States, and the numbers were rising by the hour.

Mnuchin was joined on Capitol Hill on Tuesday by White House legislative affairs director Eric Ueland and Rep. Mark Meadows (R-N.C.), the newly announced White House chief of staff. They joined key Senate Republicans around midday to review terms of the deal.

Sen. Marco Rubio (R-Fla.), who negotiated the small business portion, said it had grown to $367 billion, with inclusion of six months of loan forbearance for all small businesses adding $17 billion to the original $350 billion price tag.

“I can’t imagine there not being a deal given the differences that remain are frankly not insurmountable,” Rubio said following the meeting.

All parties would like to act swiftly, so if the Senate is able to pass a bipartisan package quickly the expectation is that the House would follow suit. House Democrats released their own larger and more generous stimulus package on Monday, stuffed with provisions that would be non-starters for Republicans such as a $15 minimum wage requirement for airlines and businesses that receive funds. But that legislation would be set aside and Pelosi would attempt to move the Senate bill through the House.

One outstanding issue Pelosi raised is that Democrats are pushing for a dramatic increase in food stamp benefits in exchange for accepting billions more in funding for the administration’s farm bailout that Republicans have included in the stimulus bill. Sen. John Hoeven (R-N.D.) said in a news release that the legislation would increase the amount the Department of Agriculture can spend on its bailout program from $30 billion to $50 billion.

A few other sticking points remained. Democrats were pushing for more money for Native American tribes. And in early drafts of the bill circulating Tuesday, nonprofits, with the exception of those that receive funding from Medicaid, would have been allowed to access the small business loans. This would effectively have excluded some health centers that provide reproductive services. Some Democrats and health advocates objected to that language — and as the legislation was finalized it appeared to have been struck.

The House of Representatives is currently out of session, and it would be tricky for House members to return en masse to Washington to vote. Democratic aides said they were optimistic that a strong bipartisan Senate vote would make it possible to pass the bill by unanimous consent in the House — a process requiring only two members present in the House chamber. But that would require every lawmaker to agree — a tall order for a $2 trillion bill touching every part of the U.S. economy.

“The easiest way for us to do it is to put aside our concerns for another day and get this done,” Pelosi said Tuesday on CNBC. “My goal always has been to bring this bill to the floor under unanimous consent.”

However, any lawmaker of either party could object, and in an early warning sign Tuesday, Rep. Alexandria Ocasio-Cortez (D-N.Y.) voiced concern about the legislation over Twitter, writing that despite “vague statements” no one had seen text of the legislation that “seems to give a *HALF TRILLION DOLLARS* away to big corporations, w/ few worker protections.”

Among House Republicans, there is similar reluctance to commit to approving a still-unseen bill, according to GOP aides familiar with internal conversations. Besides potential policy objections inherent in a $2 trillion bill, members might also resist passing a bill of that magnitude without a formal vote, the aides said — thus requiring most lawmakers to return to Washington.

If unanimous consent is not possible, aides of both parties said the most likely scenario would be a day-long vote where members would be encouraged to spread out their trips to the floor and not congregate as the vote is taken.

At least two House members and one senator have tested positive for the coronavirus, while others remained quarantined, and multiple lawmakers have voiced trepidation about returning to the Capitol.

Tuesday’s progress on the massive legislation followed four straight days of negotiations on Capitol Hill, with a deal seemingly in reach each day only to elude completion. Tempers flared on the Senate floor Monday as senators got into a near shouting match over the delays.

Congress has already passed two much smaller coronavirus relief bills: an $8.3 billion emergency supplemental for the health-care system, and a $100-billion-plus bill to boost paid sick leave and unemployment insurance and provide free coronavirus testing.

FOOTNOTE: John Wagner and Colby Itkowitz contributed to this report.