Which party will suffer most from the Westminster expenses scandal? Which will benefit? The questions are asked with a growing intensity in private by senior figures from across the political spectrum.

Of course political leaders convey no sense in public that they make such crude self-interested calculations in the midst of voters' outrage. But they do. In a minor key they are in a situation similar to when Britain goes to war. Every day they respond to unpredictable developments. At the same time they dare to hope for a 'Falklands Factor' popularity boost at the end of it all.

The answers to the questions are conflicting. My conversations in recent days suggest there is a frail insecurity on both sides. I cannot recall a time when Labour party members were more depressed. Perhaps they were as miserable when the Labour government in the 1970s headed towards defeat, but the gloom then was at least accompanied by an eruption of political energy. Tony Benn lit up the political stage, incidentally making arguments about the accountability of MPs that have now become the orthodox view. The SDP was formed. Labour had charismatic giants to inspire even after its calamitous 1983 defeat.

Now the MPs' drama seems to have drained influential Labour figures of energy. After the Damian McBride emails and the house-flipping, some of them tell me they have no idea what their party stands for any more. According to one senior Labour figure, any association with his party is toxic in the current election campaign. Apparently even parties that have worked constructively with Labour in hung councils are running a mile now they have to face the voters. Like the 1980s there is a strong anti-Labour mood in parts of the country. Some will vote above all other considerations to keep Labour out. I meet no one from the Labour side who anticipates anything other than catastrophic results.

Yet I get the impression that Conservatives are desperately worried too. Tory canvassers are reporting back that there is a "plague on both your houses" mood as next week's elections move into view. Normally the main opposition would expect to thrive when there is a lot of anti-government anger around. But now the anger extends to the Conservatives too, with their moats, duck houses and servants' quarters.

It is quite possible there will be three headlines after the elections: a wipeout for Labour; a setback for the Conservatives; and a boost for the smaller parties. For David Cameron this would be very different from the euphorically decisive headlines Tony Blair generated in elections a year before his 1997 victory.

I wonder whether the Liberal Democrats are too associated with the mainstream.

My guess is that the main beneficiary will be the United Kingdom Independence Party (UKIP), with the British National Party (BNP) making a bit of depressing headway. I would not be surprised if the Greens do fairly well too.