Many suspect the Tories, in a desperate bid to win electoral support, will go along with what is seen as utilities-bashing and pursue the possibility of special payments.
It was enough to send what have been highly charged sectors into a ragged retreat, although the blurring of the extent of the proposed liability spread the discomfort.
Many investors were prepared to settle for the lower pounds 2.5bn estimate. The possibility of a pounds 4bn hit, more than likely to be in the thick of Labour thinking, was pushed into the background. The debate was too much for the likes of Southern Electric, said to be in the sights of National Power, and Thames Water. Southern dimmed 21p to 818p and Thames slipped 12p to 526p. Seeboard, off 18p at 477p, and Yorkshire down 13p at 587p, were among others in disarray.
Manweb, struggling to resist the strength of Scottish Power, shaded to 1,004p. Scottish has 17 per cent of its target and is unlikely to go away even if the rumoured US strike occurs.
Highly geared electricity groups such as Northern, which raided the "family silver" to resist Trafalgar House (in the event forced to abandon its offer), underlined the vulnerability of the heavily borrowed groups, falling 25p to 778p.
The utilities' discomfort and another round of dividend payments almost accounted for a 7.8-point fall in the FT-SE 100 index to 3,507. Sentiment was not helped by another weak display in New York and a continuing undercurrent of unease in the foreign exchange markets.
On the drugs pitch Smith Kline Beecham outperformed following a presentation in New York on Friday by US stockbroker Bear Stearns. The US house, it would appear, has another New York investment conference planned for tomorrow and then intends to descend on London on Friday. It was enough to lift SB shares 10.5p to 634p.
Enviromed, the struggling healthcare group that has abandoned takeover talks, tumbled another 3p to 25p, a new low.
P&O, the shipping group, sunk lower in the investment water as the cross- Channel clash continued to hit sentiment. The shares fell 12p to a year's low of 485p but Eurotunnel, probably on a bear closing in Paris, firmed 1p to 99p.
Abbey National, reflecting a NatWest push, gained 8p to 536p and TSB, where take- over hopes are never far below the surface, edged forward 2p to 275p.
Dixons, the electrical retailer, enjoyed support from Barclays de Zoete Wedd and Robert Fleming Securities. The shares jumped 12p to 347p, brushing aside the possibility of more intense competition from Argos, which appears to be prepared to barge into the cut-price electrical business. Argos gained 8.5p to 494.5p on its stores initiative.
Inchcape, the international trader, slumped 17p to 324p on gloomier than expected trading tidings while Anglian, the double-glazing group, cracked 28p to 112.5p on a profit warning. Three years ago it was floated at 210p a share.
Hodder Headline, the publisher, slumped by 109p to 234p on a profit warning and Brake Brothers, the family-run convenience food group, lost 24p to 675p as it also warned about trading. Queens Moat Houses, up 0.25p at 9.5p, largely ignored renewed stories that the secretive Barclay brothers were looking at the struggling hotel group.
Blagg, the builders merchant undergoing a classic market revamp, rose 1p to 23p as it confirmed talks were under way. It is thought these could lead to the pounds 35m reverse takeover of Free Pages, a telephone sales service. The Free Pages vendors could end up with 70 per cent of the capital.
Signet, the jewellery chain, was busily traded amid suggestions that rebel shareholders Brian Myerson and Julian Treger had added to their stake, which hovers around 18 per cent. The shares shaded 0.25p to 13.75p with more than 10 million printed.
Rodime, a bet on US legislation, seems to have lost much of its appeal. The shares tumbled 3.25p to 1.25p as the company admitted that the loss of an appeal had dashed hopes of royalties on at least one of its contested patients.
Severfield-Reeve, the steel structure business, gained 14p to 112p following Independent on Sunday comment.