Efforts by Northern Ireland independent unionist MEP Jim Allister to organise opposition to powersharing between the DUP and Sinn Féin have been attacked by Ian Paisley and Peter Robinson.
Mr Allister, who quit the party after it decided last March to go into the Executive with Sinn Féin, attended an invitation-only meeting of anti-agreement unionists in Co Tyrone on Wednesday night.
Speaking afterwards, he said of the DUP that "the lure of office has clouded the party's judgment".
He added that unionist opposition to the new arrangements at Stormont was growing. "The task now is to channel this opposition - it is a work in progress."
The meeting was attended by some councillors who had quit the DUP in protest, including Robin Stirling, William Wilkinson, Walter Millar and Leslie Cubitt. Also present was victims campaigner Willie Frazer. Mr Stirling is reported to have suggested unionists voting for Sinn Féin as a protest against Dr Paisley's change in direction.
However, the DUP leadership hit back yesterday, insisting that the best defence for the union with Britain was a strong and united DUP.
Deputy leader Peter Robinson warned Mr Allister that the last rebel unionist to organise against the DUP, Mr Bob McCartney, had lost out badly at the last election.
Dr Paisley issued a detailed statement picking up on Mr Stirling's "vote Sinn Féin" idea.
"Their so-called political platform has already been rejected by the electorate and they have nothing to offer in terms of prosperity or stability for the province. Indeed many are more interested in attacking and undermining unionism than developing and strengthening the union in the longer term."
He said the DUP had strengthened the union "by facing down republicans and insisting upon our demands".
"Advocating voting for the 'shinners' in any election is the height of treachery," he added. "The union will only be safe in the hands of a strong and united Democratic Unionist team who, as the largest political party in Northern Ireland, are in the driving seat."
Despite the vociferous nature of the leadership's criticism of Mr Allister, the DUP appears not to be worried about the extent of unionist opposition to coalition with Sinn Féin.
East Derry MP Gregory Campbell, said: "I detect amongst the wider unionist community no appetite whatever for yet another unionist grouping."
It is not yet known if Mr Allister will decide to lead a new anti-powersharing party or will opt instead to form some form of watchdog-style committee to monitor the Executive and lead grassroots unionist opposition.
Mr Allister resigned from the DUP 20 years ago in a row over the selection of candidates and spent several years furthering his legal career.
He re-emerged as the party's standard-bearer at the last European Parliament election after Dr Paisley stood down. He was considered to be in line for consideration as a replacement for Dr Paisley when he stands down as MP for North Antrim.