On paper, the forthcoming by-election in Phil Woolas's old seat, Oldham East and Saddleworth, is a three-horse race. The Lib Dems trailed Labour by just 103 votes at the general election (though their poll ratings have fallen sharply since) and the Conservatives were 2,310 votes behind.
But a growing number of Tories fear that the party is planning to run a half-hearted campaign in an attempt to give Nick Clegg a morale-boosting win.
Over at ConservativeHome, Tim Montgomerie warns that Clegg's party will benefit from the decision to delay calling the by-election until Woolas's legal appeal has ended. He notes that the Lib Dems have already produced a leaflet depicting the election as a "two-horse race" between them and Labour, and that CCHQ has not been active in the seat.
The momentum is with Clegg's party.
It's not hard to imagine why David Cameron might prefer a Lib Dem to a Conservative victory. A yellow win would reassure the Lib Dem left (the coalition's weakest link) and strengthen the government's unity. Conversely, a heavy Lib Dem defeat would alarm the party's increasingly rebellious backbenchers and put Cameron under pressure to make greater concessions.
But those Conservatives desperate to achieve a majority next time are angered by their leader's casual attitude to an eminently winnable seat. Cameron must tread carefully if he is not to alienate his own grass roots.