Senior Conservative MPs fear that David Cameron is diluting their party's opposition to electoral reform in an attempt to boost Nick Clegg's chances of winning a Yes vote in the referendum due in May.
They are worried that the Tories will run a "softly, softly" campaign against a switch to the alternative vote (AV) system, even though Mr Cameron promised his MPs that the party would fight hard to retain the present first-past-the-post system.
The Independent has learned that the Conservatives have so far earmarked only £250,000 for the No campaign – a small proportion of the £5m both sides in the referendum battle will be allowed to spend in the 10 weeks before the public vote. Baroness Warsi, the party's chairman, is expected to be challenged about its commitment to the No cause today when she addresses the weekly meeting of the 1922 Committee of Tory MPs.
There are growing fears among Tory backbenchers that some Cameron allies would be privately relaxed about a Yes vote in the referendum, since it would give Mr Clegg a big prize and almost certainly ensure that the Coalition lasted until the next election in 2015. In contrast, a No vote could provoke demands from some Liberal Democrat activists for the party to pull out of the Coalition.
Tory traditionalists also fear a switch to AV would increase the chances of a permanent alliance between the two Coalition parties, as favoured by some Tory modernisers. Under this system, people mark the candidates in order of preference – the last-placed person drops out and second preferences are redistributed until one candidate secures more than 50 per cent of the votes.
Traditionalists believe the introduction of AV would lead to an informal anti-Labour pact, under which Mr Cameron encouraged Tory supporters to make the Liberal Democrats their second choice, with Mr Clegg urging his party's backers to put the Tories in second place.
Mr Cameron's critics are already alarmed by the Tories' decision to soft pedal in last month's by-election in Oldham East and Saddleworth, where thousands of natural Conservatives backed the Liberal Democrats, ensuring they came second behind Labour and avoided a humiliating third place.
The critics are worried that, as The Independent revealed last week, some Tory Cabinet ministers advocate similar tactical voting at the next general election designed to save the seats of the 57 Liberal Democrat MPs. They say that would infuriate and demoralise Tory activists in those constituencies. Mark Pritchard, secretary of the 1922 Committee and MP for The Wrekin, said yesterday: "The Prime Minister has made explicit commitments on his role in the No to AV campaign, which I am sure he will honour. There is a need for greater clarity and encouragement on where and when finding for the campaign will be given by Conservative Campaign Headquarters. Some funds have been allocated but many colleagues increasingly feel these are insufficient."
Brian Binley, the committee's treasurer and a member of the Conservative Party's board, said that there was "real concern" among Tory MPs that the party might soft pedal in the referendum.
"There has been serious concern about the general unwillingness of the party to get behind the No to AV campaign. I am sure David Cameron is intent on keeping his word. I and other Conservative MPs who oppose AV would like to see a more robust attitude."
Fears of a permanent Liberal-Conservative alliance are contributing to a sullen mood among many Tory MPs. Their other complaints include allegations of bureaucracy and delays at the Independent Parliamentary Standards Authority (IPSA), the new body which handles MPs' expenses. Mr Cameron has given IPSA until April to put its house in order.
Backbench Tories are also rebelling over the party's whipping operation, claiming they are ordered to remain at Westminster to ensure the Government wins big majorities in Commons Commons votes while their Liberal Democrat "partners" are allowed to return to their constituencies.