As I watched Hank Paulson last weekend, I was reminded of an old story about the Duke of Wellington.

Recalling in later years his first Cabinet meeting as prime minister, the Iron Duke is supposed to have expressed bewilderment: “I couldn't understand it,” he said. “I called them in, gave them their orders and they wanted to sit and discuss them.”

It might, I fear, be apocryphal, but like all such stories it still captures something essential - in this case, the imperiousness and bluff ingenuousness of the old Duke as he made the awkward transition from military genius to mere politician.

Mr Paulson is having a similarly jarring experience this week.

On Saturday he called in the leaders of Congress and presented them with their orders. They were to give him $700 billion of taxpayers' money (maybe more) so that he could fix the wreckage in the US financial system. He would spend the money exactly as he saw fit and his decisions would not be open to either political or judicial review.

Oh, and one other thing: he needed the money by Friday.

Imagine his horror, when, just like the old Duke, he had to listen as his interlocutors told him they might want to think about this for a while.

Despite a steadily rising chorus of dissent against the Paulson Plan, the betting in Washington is that the US Treasury Secretary will largely get his way. Critics are scrambling to come up with alternatives to resolve the mess, but Mr Paulson has time and chaos on his side.

It is unlikely that anyone will really have the time to come up with another, evidently better plan by Friday and the positive reaction of financial markets even to the hint of a rescue is holding members of Congress hostage only six weeks before they face the voters.

The best that Congress can hope for is to impose some small limitations and to extract some concessions from the Treasury between now and the end of the week.

On Wall Street, this is being treated with the usual disdain that bankers reserve for politicians. They're talking derisively about another congressional “Christmas Tree”, loaded with all kinds of ornaments for the benefit of their constituents.

Now I'm not usually one to side with politicians over business people, but this strikes me as a bit rich, coming from a bunch of geniuses who have spent the past ten years loading up their own Christmas trees and now want the US taxpayer to pay for them.

It's early days in the negotiating process, but here's what Congress seems likely to demand as the price of its agreement to the bailout plan.

There will surely have to be a little more political oversight of the Treasury's purchases of the toxic waste in banks' balance sheets than is envisaged.

No one I've spoken to in Washington in the past few days thinks that the Treasury Secretary and his successors should be given the kind of financial authority that would have made King George III blush back at the time of the Boston Tea Party.

They're going to insist on some sort of protection for taxpayers, at least in the form of detailed reporting requirements from Treasury to Capitol Hill.

There's also a good chance that the final bill will have to include some support directly for those homeowners facing foreclosure. This seems to me a political necessity.

The Paulson Plan is not going to be popular out in the country when people realise that it is going to cost them upwards of $5,000 per family. Assuaging that anger is going to mean sending money to the needy, too.

Democrats may also get their way in demanding some kind of limit on remuneration for the executives of those financial institutions in receipt of the government largesse.

The really big question, however, is how far Congress wants to get involved in the details of how the toxic asset purchase plan operates.

There's already been loud complaining that non-US financial institutions will benefit. Will British banks such as HSBC find themselves being propped up by the US taxpayer?

Treasury officials made clear yesterday that they think the qualification should be a substantial presence in the American market, which would surely include the big British and European banks. Members of Congress from places such as New Jersey and Illinois may well be reluctant to appear to be agreeing to send the many employees of European banks in their districts to their fate.

But they are heavily outnumbered by members of Congress with no foreign banks and lots of angry Americans in their constituencies.

The principal uncertainty, though, is how exactly the Treasury will buy the asset-backed securities that are at the heart of the scheme. If it pays a current market price for those assets, it is not clear that it will help undercapitalised banks much, since it is the present valuations that are doing so much damage to their capital. If it buys at well above the market rates, it will help banks with their capital but at what could be an even higher cost for the taxpayer.

Some congressional staff members who have been involved in the discussions say Mr Paulson is making it clear in private to the politicians that the Government expects to pay above the current market prices. Officials insist that, over time, as the immediate panic fades, the prices of these assets will rise, reducing the cost to the taxpayer.

No wonder that, like Wellington's sceptical Cabinet members, the politicians want to hear a bit more about this plan before they salute.

gerard.baker@thetimes.co.uk

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