Tory MP Gavin Barwell, fighting a marginal seat in the election, has urged backers not to mention "the Conservative Party or David Cameron" in letters of support.
The Croydon MP wrote to constituents asking them to sign letters to friends and neighbours endorsing his re-election but suggested they would be "more effective" if they did not mention the Prime Minister or his party.
The letter, widely circulated on twitter, read: "I'm not asking you to write a political letter - in fact, it'll be much more effective if it doesn't mention the Conservative Party or David Cameron."
Mr Barwell said it was "ridiculous" to suggest that he did not want to mention Mr Cameron during his campaign to retain the seat.
He said: "I am one of the strongest supporters of the Prime Minister, he is all over my literature.
"I'm fighting a marginal seat so obviously I'm trying to build a coalition between people that are solid Conservatives, people who are undecided but prefer David Cameron to Ed Miliband and people who I hope will think I have done a good job as their local MP."
Sarah Jones, the Labour candidate for Croydon Central, said: "It's a sign of real desperation that Gavin Barwell is actively telling people not to call him a Tory. He's trying to pull the wool over people's eyes."