President Bush is tonight due to deliver a rare prime-time televised address to convince Americans - and a hostile Congress - of the urgent need to pass his administration's $700 billion rescue plan for the country's stricken financial sector.

As intense negotiations continued between the White House and a deeply sceptical Capitol Hill on the colossal bailout - which could be passed with heavy modifications by next week - Mr Bush cancelled a fundraising trip to Florida to work on the speech.

Despite vocal opposition by both Republicans and Democrats during two days of testimony on Capitol Hill by Henry Paulson, the US Treasury Secretary, and Ben Bernanke, the Federal Reserve chairman, a consensus was emerging tonight that some sort of deal had to be reached soon to avert a financial meltdown.

With Congress due to adjourn for the election season recess on Friday, Republican and Democratic leaders said that negotiations could extend into next week, so long is the list of concessions and changes being demanded on Capitol Hill. Yet even some of the most sceptical senators and congressman conceded that a failure to deliver some sort of rescue package could trigger further economic turmoil.

"The consensus is: A, people don't like it; B, it will have to change; and C, we have to do something," said Charles Schumer, the Democratic chairman of the joint economic committee.

Richard Shelby, the senior Republican on the Senate Banking Committee and one of the most outspoken critics of the plan, said tonight: "I certainly was not satisfied by Chairman Bernanke and Secretary Paulson. As it stands I have no intention of supporting this. I think something will probably pass but it will need to be reconfigured to make it palatable."

Mr Bush's spokeswoman, Dana Perino, said the President was weighing how to best share his view of the urgency of the situation. She said the nation "could be facing financial calamity" without what she called bold and decisive action.

Yet Mr Paulson and Mr Bernanke, on Capitol Hill to sell the plan, continued to face bipartisan anger over their proposal for the biggest government intervention in the financial markets since the Great depression, especially to their calls for Congress to sign off on such a massive bailout by the end of the week. Some Democrats even compared the calls for immediate action to what they claimed was the way the nation was rushed into the Iraq war.

Democrats and Republicans dislike the bailout for a variety of reasons, but are unified by one harsh political reality: most face the voters in their own districts in six weeks time. Many are receiving hundreds of angry phone calls from constituents daily, expressing outrage that the titans of Wall Street - widely blamed for the financial chaos - are being bailed out, while millions of working families are having their homes repossessed.

Newt Gingrich, the former Republican House Speaker and a fiscal conservative, called the package a "dead loser", and predicted with a touch of hyperbole that any politician who voted for it would face defeat on November 4.

In essence, Democrats are demanding that the plan contains an oversight board to monitor the programme and provisions to help homeowners avoid repossession. They also want to see taxpayers given an equity stake in the bailout if the toxic assets being purchased by the government eventually become profitable. Mr Paulson has indicated that he is open to negotiating on all three provisions.

The greatest opposition is from conservative Republicans in the House of Representatives, who cannot stomach what one described as a "socialist" measure, and another described as "cash for trash".

A greater sticking point is calls by both Republicans and Democrats for strict limits on executive salaries. Mr Paulson is opposed to the idea because he fears banks will not participate in the scheme if it is included.

Democrats probably have enough votes to force through a measure on their own, but warned that they will not pass any bill without significant Republican support. "It's their problem. It's their bill. And they're going to have to figure out if they can support it," said Nancy Pelosi, the Democratic House Speaker.

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