The tone was set in a St. Patrick’s Day phone call between Nancy Pelosi and Mitch McConnell, when the House speaker requested the top four congressional leaders to begin negotiating a package rescuing the economy from the effects of the coronavirus pandemic.

McConnell told her no — he would bargain exclusively with Senate Democrats and their leader, Sen. Charles E. Schumer (N.Y.).

But that did not settle the issue, and when Pelosi and McConnell ultimately met face to face the following Sunday at an all-leaders meeting he had called to outline his bill, Pelosi showed up with “a laundry list” of what the Senate majority leader and other Republicans viewed as liberal demands unrelated to the crisis.

From the perspective of Schumer and Pelosi, McConnell’s bill under construction offered help for corporations but not much for the average American. There were no worker protections on the corporate rescue funds. No state and local bailout fund. Not enough spending for hospitals.

The two sides went their separate ways after the meeting. Senate Democrats blocked a procedural vote, angering Republicans. Pelosi declared she would write her own bill — giving Democrats something to rally around.

But with the stock market tanking and the U.S. death toll climbing, congressional leaders and Trump administration officials managed to compromise with trade-offs such as more generous unemployment insurance and restrictions on the corporate help that satisfied both parties.

And on Friday, the House voted unanimously to approve the measure, a $2.2 trillion emergency aid package that is the costliest in U.S. history, forged amid economic conditions that worsened by the moment, a tempestuous president and tempers that flared in a Congress rattled with genuine fear of a pandemic.

The first step requested of Congress by the White House was on Feb. 24, a comparatively paltry $1.8 billion in new spending to address rising health concerns stemming from the virus. Now — just one month later — Congress sent Trump a package that is more than 1,000 times greater, underscoring the frantic scramble from policymakers trying to arrest the economic calamity.

There were plenty of hiccups, up until the moment the chief negotiators finalized the deal.

As Schumer, Mnuchin and Eric Ueland, the White House director of legislative affairs, met Monday night to smooth out an agreement on the $2.2 trillion economic rescue package, thousands of phones across Washington started buzzing.

The president had tweeted.

“Republicans had a deal until Nancy Pelosi rode into town from her extended vacation. The Democrats want the Virus to win?” Trump tweeted. “They are asking for things that have nothing to do with our great workers or companies. They want Open Borders & Green New Deal. Republicans shouldn’t agree!”

Schumer, who had spent days negotiating with the administration, felt that tweet did not reflect the reality of the progress they had made. After being informed by his staff of the 279-character missive, Schumer delivered — via speaker on Mnuchin’s phone — a pressing message: “For the good of the country,” Schumer told Trump, according to an official familiar with the call, “you should not be attacking anyone.”

After Trump hung up, Schumer quipped to others in the room: “He must’ve been watching TV.”

Both sides claimed credit for the bill. Senior Republicans portrayed the legislation as a largely bipartisan, yet right-of-center package, and Democrats argued that they wrested the measure away from one that shortchanged workers and lacked accountability over corporations.

“The major advantage that we had is, this is a crisis. And the Republican philosophy of little government, let the private sector do everything, diminish government, just doesn’t work,” Schumer said in an interview with The Washington Post. “So we sort of naturally had the upper hand.”

For McConnell, it was a chance to assert the power of his Republican majority after the Senate mostly took a back seat in the previous $100 billion emergency coronavirus bill. Forgoing any concerns about the deficit, McConnell and administration officials were encouraged by a president who urged negotiators behind the scenes to “be bold, be brave and go big.”

That second tranche of spending, which cleared Congress on March 18, was largely a product between Mnuchin and Pelosi and loathed by several Senate Republicans over paid family leave provisions. But McConnell, recognizing the money had to go out immediately, told his members to essentially swallow the bill and look toward the next, much more expansive economic package that lawmakers were under pressure to craft.

On that package, McConnell told Pelosi on that March 17 call, he planned to negotiate directly with Schumer.

McConnell canceled a scheduled Senate recess, tapped key GOP senators on separate task forces to negotiate the four primary sections of the relief package and urged them to get some Democratic buy-in. Still, he was confident the final product largely reflected conservative priorities.

“They did do that for a couple days, made themselves look very foolish, but that did not change the core product — which was mostly Republican,” McConnell said of Democrats in an interview with The Post.

The sweeping rescue package injects enormous amounts of federal spending into the American economy — sending checks to more than 150 million U.S. households, establishing massive loan programs designed at keeping both small and large businesses afloat, and dramatically expanding unemployment benefit programs while upping spending for hospitals struggling for basic equipment.

Yet after countless twists and turns as it moved through the Senate, one last complication awaited Friday in the House as a single GOP member forced lawmakers to return to Washington en masse to ensure a quorum would be there to vote — even though ultimate passage of the bill was inevitable and the gathering was contrary to public health advice.

Rep. Thomas Massie (R-Ky.) raised procedural objections that required a majority of the House to be physically present to swiftly reject his request. Once they did, the House passed the legislation by voice vote shortly before 1:30 p.m. Friday and sent it to the president who signed it hours later.

That last-minute scramble was an appropriate ending for frantic negotiations that were fraught with tensions from the beginning.

From the start, McConnell believed it was only fair the Senate take the lead in drafting the third phase of the coronavirus legislation and that the Democratic-led House accept it, considering the Senate had done the same for the earlier package despite GOP protestations. That line of reasoning infuriated Democrats, who criticized McConnell’s own decision to stand on the sidelines for the second phase, then leave Washington to attend an event in Kentucky featuring Supreme Court Justice Brett M. Kavanaugh.

Key senators negotiated for days in separate task forces established by McConnell. There was enough progress that this past Saturday, Mnuchin told GOP senators during a meeting at the Capitol that he had just left Schumer’s office and believed there were no major issues that would prevent them from reaching a deal later that night.

But then that night, McConnell had appeared to shut down the negotiations and prepared to release his own legislation. On Sunday, Pelosi — who had flown in the day before on an Alaska Airlines flight with her security detail and a dozen others on a plane that usually seats 200 — felt it was bizarre that McConnell and Treasury Secretary Steven Mnuchin insisted there was a deal, even as she and Schumer detailed a list of provisions they felt were problematic.

It spiraled further downward during the meeting with the four leaders on Sunday, after McConnell declared Republicans would release their plan — crafted in part with Democratic input — and Pelosi said she would produce her own bill.

“It underscored why I didn’t want to start with four corners to begin with,” McConnell said, referring to the quartet of congressional leaders. “What it did was slow down the process for three days to get to an outcome that we could both buy in to.”

When Schumer hosted a Democratic lunch in the spacious Kennedy Caucus room in the Russell Senate Office Building later that day where both parties had shifted their party meetings to allow for more distancing among members, he stressed that the plan McConnell had released earlier was largely a corporate bailout that did little for workers.

Yet, even after those contentious meetings — and the angry floor speeches, two Democratic filibusters and an unusually hot-tempered McConnell — the negotiations continued apace.

“It was hot on the floor and cool in the room,” said one senior administration official, speaking on the condition of anonymity to talk freely.

All throughout, the fear among senators, particularly those from hard-hit states, was palpable.

When news broke during a Democratic caucus lunch on Sunday that Sen. Rand Paul (R-Ky.) had tested positive for the coronavirus, Schumer promptly broke up the meeting, and senators dispersed to their offices to continue via conference call. The Strom Thurmond room in McConnell’s wing of offices — where some of the meetings had taken place — had been disinfected and left a strong odor of cleaning solution; the negotiating team ultimately moved to a separate meeting space named after former president Lyndon B. Johnson.

Sen. Patty Murray (D-Wash.) was concerned well before the rest of her colleagues based on what she had witnessed in her home state, where most of the early coronavirus cases were concentrated.

Even during the impeachment trial that consumed the Senate for the first several weeks of the year, Murray was worried other senators were not taking the emerging public health crisis seriously. The No. 3 Senate Democrat quickly stopped going to in-person meetings and urged Schumer to hold conference calls instead. She was adamant her own aides stay off the congressional premises as much as possible.

At a Feb. 26 retreat with other Senate Democrats, Murray delivered a bracing message as headlines began to trickle out about the mysterious outbreak at a nursing home in Kirkland, Wash.: “What’s happening in Washington state is coming to you.”

In the subsequent weeks, that urgency spread to other states and its leaders, as New York and California joined Washington state as the epicenters of the pandemic. The frustration and desperation for massive federal assistance was underscored in a Wednesday call between New York Gov. Andrew M. Cuomo (D) and members of the state’s House delegation, during which the governor repeatedly slammed the bill — that Schumer, the state’s senior senator, negotiated — as insufficient.

Targeting Schumer, Cuomo said he knows the famously media-savvy Schumer wants to do a news release that he got something passed, but then the governor had to figure out how to run a state budget — and that he couldn’t do anything with the money allocated to New York under the package.

“I’m paying the whole g--damn bill here,” Cuomo told the New York House members on the call.

Cuomo urged the House delegation to get New York more money, and they responded that they would try. But ultimately, the House passed the bill unchanged from the version Cuomo lambasted.

“What happened was that we kept our eye on what needed to be done, which really fit the national need — much more money for hospitals than they proposed, far more accountability on corporate bailouts than they proposed,” Schumer said in The Post interview. “Money for state and localities, which they had none of. And more stuff for working and unemployed people, and they really, our Republican friends, didn't have much to say.”

As of Friday evening, more than 100,000 Americans have contracted the virus, with more than 1,500 deaths. Multiple large companies have been brought to their knees. Millions of Americans lost their jobs, and economists predicted a second coming of the Great Depression as the U.S. economy screeched to a halt.

When it came time to vote late Wednesday, senators were reminded that the crisis was everywhere, including inside the Senate chamber. On the Republican side of the clerk desk, where votes are tallied, GOP senators were greeted with a white sheet of paper that had, in blood-red design, a two-word greeting: “SOCIAL DISTANCE.”

Across the table, Democrats were greeted by a more complex design with stick figures explaining how far apart they should stand, with a similar two-word admonition: “CREATE SPACE.”

As the last two votes unfolded, Sen. David Perdue (R-Ga.) took over as the presiding officer, always a cumbersome task, but one that now has a different regimen involved: He reached under the desk to grab a large disinfectant sheet, then wiped down the desk to assure no viral germs were there.

The legislation had easily passed, with 88 yeas and not a single vote of opposition. Murray stood on the edge of the chamber, unwilling to enter a place that was about to close up for its own deep cleaning. Most senators do not know when they will return to vote again.

She held her finger up waiting for a clerk to see her off in the distance, before finally Schumer pointed at clerks to recognize her.

She flashed a thumbs up.