Jim Nicholson has launched his party's European manifesto
Jim Nicholson has claimed he is the only unionist who can top the poll at the European election on 4 June.
He was speaking at the launch of the joint Conservatives and Unionists manifesto, attended by the former Tory leader William Hague.
They want a referendum on the Lisbon Treaty and oppose the UK adoption of the Euro currency.
Mr Nicholson also called for the return of social and employment legislation to the control of the British government.
Mr Nicholson said: "Jim Allister is taking a lot of votes off the DUP.
"The DUP are making a lot of topping the poll - I think it sends the wrong message out if Sinn Fein do top the poll, and I think I am the only unionist left who can do so."
Mr Hague said the electoral pact between the two parties represented a natural family brought back together.
The shadow foreign secretary spoke of the common cause shared by both parties, adding that Mr Nicholson would be an integral part of a national team.
Mr Nicholson said unionists he had canvassed on the doorsteps had welcomed the party's links with the Conservatives.
Absent from the launch at Belfast's Waterfront Hall was the party's only MP, Lady Hermon, who is opposed to the electoral arrangement.
Mr Nicholson said he was not sure if Lady Hermon would join him for canvassing but if she did not, it would not be his fault.