A by-election should be held following the resignation of a Ballymoney DUP councillor to test support for power-sharing with Sinn Fein, Jim Allister said today.
The Traditional Unionist Voice (TUV) leader warned that his party aimed to make an impact following decision of the DUP's Roy Wilson to stand down.
Mr Allister has promised to stand for the Westminster North Antrim seat and is expected to put up a tough challenge in Ballymoney.
"My expectation is that there will be a by-election," he said.
The TUV took almost 70,000 votes from the DUP at the European election.
The Dromore by-election in February 2008 helped to build the profile of Mr Allister's hardline unionist party.
Ballymoney is in the DUP's North Antrim heartland, and Mr Allister said he was looking forward to a similar challenge.
He said Mr Wilson had stood down from the local authority in "principled opposition" to the DUP's politics and added he looked forward to testing the waters in the North Antrim constituency.
Mr Allister was the DUP's Member of the European Parliament but quit the party in 2007 over Stormont power-sharing with Sinn Fein.
In last month's European election Mr Allister failed to hang on to his seat and DUP candidate Diane Dodds was elected.
However, the DUP's first preference vote fell to 18.2%, from 32% in 2004. It appeared most of those votes went to Mr Allister, who attracted 66,000 votes.
He has said in the next general election he will take on the DUP in the North Antrim constituency held by Ian Paisley since 1970.
DUP head of council at Ballymoney Evelyne Robinson said: "My awareness is that he (Mr Allister) is still a member of the party."