The breakthrough on Capitol Hill that delivered a tentative deal on the $700 billion rescue plan for the US economy came just after midnight, following hours of tense negotiations, shouting matches, phone calls to President Bush, and even an emergency delivery of pizza and burgers.

The verbal deal, which was posted online in written form last night and will head to the House of Representatives for a vote as early as today, came after one of the most intense and extraordinary sessions of legislative wrangling in modern times. Hank Paulson, the exhausted US Treasury Secretary, finally persuaded the Republican and Democratic leaderships to agree to a compromise hours before the Asian markets opened.

Although many conservative Republicans remain opposed to the deal, both sides now hope that there is enough cross-party support — in both the House and the Senate — for Mr Bush to sign into law within a matter of days the greatest government financial intervention since the Great Depression of the 1930s.

Early this morning, it appeared that enough of the Republicans were falling in line behind the rescue package to make its passage more assured.

After compromises from the White House, Democrats and Republicans, the deal will effectively give Mr Paulson $350 billion immediately to start buying toxic mortgage-related assets, while the second $350 billion will have to be approved by Congress. It includes limits on pay and severance packages for executives, strict oversight of the spending, profits for taxpayers should the plan work, and powers for the government to renegotiate mortgages for struggling homeowners.

One factor believed to have clinched the deal was a proposal by Nancy Pelosi, Speaker of the House, that if the plan was not profitable within five years, then the Wall Street institution bailed out will have to begin reimbursing taxpayers.

“The party is over,” she said later. “The era of golden parachutes for high-flying Wall Street operators is over. No longer will the US taxpayer bail out the recklessness of Wall Street."

After a rebellion by House conservatives stymied hopes of a deal on Thursday, Mr Paulson resurrected the talks at 3pm on Saturday in the second-floor Capitol Hill office of Mrs Pelosi, just off the Rotunda. By the time a deal had been struck nine hours later, the Treasury Secretary’s original three-page plan — delivered to Congress 10 days ago — had swelled to more than 100 pages.

From 3pm to 5.30pm, Mr Paulson met members of both parties around the huge table in Mrs Pelosi’s conference room, under a portrait of President Abraham Lincoln.

Also present at the table were party and legislative leaders, including Mrs Pelosi, Roy Blunt, representing House Republicans, Judd Greg, the New Hampshire senator and senior Republican on the Budget Committee, and an array of other Democrats, including Barney Frank, chairman of the House Financial Services Committee. At one point Max Baucus, the Democratic chairman of the Senate Committee on Finance, shouted at the Treasury Secretary about the curbs on executive pay.

Mr Paulson became so vexed by the fact that Democrats outnumbered Republicans by nine to two that he rang Mr Reid to demand that some leave. Mr Reid refused.

Later, the group split up and decamped to three separate rooms, with Mr Paulson setting up a quasi-command centre in the chambers of John Boehner, the Republican House Minority leader, sitting on a sofa surrounded by aides in chairs.

In nearby corridors, bemused and startled tourists stared as cameramen barged each other aside to get footage of the politicians huddling outside the negotiations. In a sign that the negotiations were entering a critical stage, early in the evening an aide to Mrs Pelosi demanded the surrender of BlackBerrys by all her staff — they were placed in a bin — so that no details of the plan would leak out.

Meanwhile, phone calls were repeatedly being made, including ones between Mrs Pelosi and Mr Bush, to and from Mr Paulson and John McCain and Barack Obama, and between the two candidates and senior members of their respective parties.

There were even calls placed to Warren Buffett, the hugely respected investor, who had cautioned that a failure to reach a deal would trigger “the biggest financial meltdown in American history”.

Mr Bush, who gave warning last week of financial catastrophe if a deal was not reached, tried to convince Americans in his weekly radio address that the plan was not simply a bailout of Wall Street.

“The rescue effort that we’re negotiating is not aimed at Wall Street — it’s aimed at your street,” he said.

Just after 8pm, pizzas were delivered to the Paulson team in Mr Boehner’s office. Democratic staffers ordered burgers from Five Guys, while a platter from the sandwich shop Cosi arrived at Mrs Pelosi’s suite of rooms.

“This is Saturday night,” said Mr Conrad to reporters at one point. “You have the Secretary of the Treasury. You have congressional leaders. And there’s a reason we are here — because there’s a great feeling of responsibility to get a package as quickly as we can while doing it as well as we can.”

By 11pm, all had gathered again in Mrs Pelosi’s office to finalise the deal. They emerged in front of the cameras with Mr Paulson at 12.30am to announce that they had a tentative agreement. “We’ve made great progress, but we have to commit it to paper before we can formally agree,” Mrs Pelosi said.

Mr Paulson, bags under his eyes, said: “We’ve been working on this a long time. We’ve still got more to do to finalise it, but I think we’re there.”

Down to details

Size Mr Paulson had wanted $700 billion in one go. But the draft legislation proposes instalments and means that he will have to ask for more when needed. He will get $250 billion initially, another $100 billion after writing a progress report to Congress, with a final $350 billion available later

The taxpayer Rebel Republicans want Wall Street to pay for more of the bailout. The draft Bill includes an insurance scheme, which would force troubled banks to pay a premium to the US Treasury in return for Washington guaranteeing their assets.

However, included in the Bill is a critical new measure designed to protect the taxpayer: If the $700 billion is not paid back to the taxpayer through the sale of toxic assets or through the value of the Government's stakes in the banks within five years, the financial institutions that benefited from the bailout must pay the shortfall back

Oversight The draft Bill will include measures to set up an oversight board, made up of lawmakers from both parties. Any transactions by the fund would have to be made public

Executive pay Democrats have got their way on capping executive pay. The Bill will tax executives more heavily if they receive multimillion-dollar severance packages. Washington will also remove some tax breaks for banks if they benefit in a particular way from the bailout, making it more expensive to give executives salaries of more than $500,000 a year. Washington also gets the right to claw back money from executives retrospectively

Housing Some Democrats wanted to force lenders to cut interest rates to help struggling borrowers. It is believed that this has been replaced with an extended tax holiday for those who cannot make their repayments and a clause allowing the Treasury to change the terms of mortgages

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