The Conservative rival standing against Nick Clegg says there is ‘no pact’ to keep Clegg in the seat after a former Tory candidate backed him.
Liberal Democrat leaflets featuring John Harthman - who came second in Sheffield Hallam in 2001 as the Conservative candidate - have been sent out to voters.
In the leaflets Mr Hartham urges people to vote for Mr Clegg.
Nationally commentators have noted the Conservative campaign in Hallam seems low-key, compared to those of Mr Clegg and Labour’s Oliver Coppard.
Asked if there was a ‘Coalition pact’, Ian Walker, the Conservative candidate for Hallam on May 7, said: “We decided to start our campaign once the election was called so people didn’t get fed up.
“I can assure you I’m not rolling over and letting the Liberal Democrats have a free run at this - there is no pact that I’m aware of.”
Mr Walker also said that a recent poll had shown the Conservatives were ‘neck-and-neck’ with the Liberal Democrats and that the leaflet was encouraging people to ‘vote out of fear.’
Mr Coppard added: “I think it is a desperate attempt to shore up his vote.
“In 2010 Nick Clegg was asking for Labour voters to support him to stop the Tories getting in Government, now he is asking Tory voters to stop Labour getting in.
“It’s all about him, rather than Sheffield - people are not going to be swayed.”
Speaking to BBC Radio Sheffield, former city councillor Mr Harthman said he had been approached by the Liberal Democrats about the leaflet after he wrote a letter to The Times saying people should vote for Mr Clegg because he had been a ‘good MP and good for the country.’
He added: “I don’t think there is a realistic chance the Conservative candidate will win this time.”
A spokesman for Nick Clegg said: “Nick attracts support from a wide range of political backgrounds because people recognise he has been a good local MP for the last ten years and has delivered for Sheffield Hallam.
“John Harthman is someone who clearly recognises Nick Clegg is the best candidate for Hallam and we are grateful for his endorsement.”