Ulster Unionists face the prospect of Sinn Féin becoming Northern Ireland's largest party, Mr Jeffrey Donaldson said.
"With the SDLP losing ground to Sinn Féin, it is also worth remembering that if unionists do not get their act together then there's a very real prospect of Sinn Féin/IRA becoming the biggest party and that really would be the nightmare scenario," he said.
The Lagan Valley MP is trying to force his party to apply sanctions to Sinn Féin because of alleged breaches in the IRA ceasefire.
In an interview published in a Belfast newspaper today, Mr Donaldson said tomorrow's meeting of the ruling council was a crucial staging post ahead of the most important election campaign in its history.
Although Mr Donaldson insisted that he was not about to challenge Mr David Trimble's leadership, he said the policy of continuing with the status quo was unthinkable.
"For me that is not an option. It's an abandonment of political reality and our responsibility to the people who elected us".
Mr Trimble and Mr Donaldson have circulated letters calling for the support of the 860-strong council tomorrow in what is becoming a head-to-head clash between the Yes and No camps of the party.
PA