Former Prime Minister John Major has warned Tory voters that a vote for the UK Independence Party is a vote for Labour.
Mr Major says that a vote for UKIP is a vote for Labour
"If anybody wants to see the Labour party returned to power, then go out and vote UKIP," he told BBC1's Breakfast with Frost on Sunday.
He said Tory voters would vote for UKIP because they felt strongly about the issue of the European Constitution.
But he warned that Europe was UKIP's only policy.
"They are a single issue party on Europe," he said, and similar to the BNP and former Referendum Party by being "on the periphery of politics".
"I think the best way to deal with those parties is to deal with the whole issue of policy. Other than their particular subject, they have nothing to say," Mr Major said.
Meanwhile, Robert Kilroy-Silk continued his campaign to run UKIP by urging his supporters to force a leadership challenge.
"The members have the ability in their hands to force an extraordinary
general meeting and through that to force an election," he told GMTV on Sunday, adding that the leadership issue had reached "stalemate".
"I think we have a great political moment and I think we have the opportunity
with UKIP to be a serious political party and to have a major impact on British
politics," Mr Kilroy-Silk said.
"People are looking for something fresh, new, and I
think we could have been that party... the moment is slipping away," he warned.
Mr Kilroy-Silk says he has the support to lead UKIP
Party leader Roger Knapman has called on Mr Kilroy-Silk to abandon his leadership aspirations, saying internal polls show he does not have enough support.
Mr Knapman said an internal party poll showed 109 chairmen wanted him as leader, while only 25 wanted his rival.
He told BBC Radio 4's Today programme earlier in the week that the leadership had been "sorted out".
He said that Mr Kilroy-Silk was wanted "back in the fold, but as a team player, and team players must cease attacks on their own party on a daily basis".
"We hope he will be a good team player, but if he can't be a good team player, he owes it to himself and to the party to look at his future carefully."
But Mr Kilroy-Silk told GMTV that the poll did not reflect the views of the 28,000 party members.
"[The leadership] claimed to have more support than they had," he said.