The main worry being that Cameron winning is not the lesser of two evils, but the middle of three: best being Labour win, worst a further right Tory administration. So the worry is that Cameron doesn't win and then we get a David Davis/Liam Fox/Andrew Rosindale (God forbid) -lead administration who couldn't help but win. Of course, if we get a reverse Blair it won't be so bad i.e. a leader further to the political centre than their party who is pretty much indistinguishable from someone on the other side.
Evidence that this fear is well-founded can be found in this paragraph:
"On the influential Tory website ConservativeHome, some contributors are breathless with the shifting polls' implications. "There is a huge problem here," says Victor M. "If Tory HQ don't solve [it] as of now, we are doomed to five more years of the fat Scottish droner." David Alan says: "We are flatlining at around 36/37%. That is frankly a disaster. If we do win it's going to be as a minority government or with a very small majority. Either way Cameron will have a bust-up with [the] party soon after, so allowing Labour back in." Craig says: "Cameron is a bloody beauty queen but a disaster of a politician. We have been sold down the river by him. He can't beat Brown. We should get [Oliver] Letwin in now." Angry Womble replies: "It's already too late . . . David Davis would have made a better leader." Jacqui D says: "Let someone else take the plunge - Boris [Johnson] would have no such qualms.""
"Compared to most senior ministers in elderly governments, many of Brown's key allies are young. And many of them - Ed Miliband, Ed Balls, Yvette Cooper - are more left-of-centre than their Blairite predecessors; were Labour to continue in office, Cruddas expects them to continue to move cautiously in that direction. Judging by the budget's tax rises for rich property owners, Brown and Darling intend to do so as well."
An excellent point
"Yet governments that win an unexpected extra term tend not to end happily. Gould is mindful of what happened to Major after 1992: "If Labour won this time, would voters wake up the day after the election and say: 'God, five more years of Gordon Brown'? I think they would.""
My fear exactly
"I reckon the best thing the Labour party could do would be to subtly get the message out - officially denied of course - that if they win Gordon Brown will serve a limited period as prime minister before resigning in favour of Balls, Miliband etc.
He could waltz off into the sunset to lead the World Bank or the IMF having achieved his ambition of winning a general election.
Time to start planting some stories in the Guardian."
Now that IS an interesting possibility. Gordy would need to be dragged out kicking and screaming, he won't go and he'll take the whole party down with him. But if it could be achieved, it would probably benefit the party and the country. Even david Miliband replacing him, which doesn't exactly fill me with joy