Basil McCrea, Tina McKenzie and John McCallister at the launch of NI21 in June 2013

NI21 is in total chaos as voters hit the polls after the party was branded crazy and dysfunctional by its own deputy leader – who was then told to consider quitting by his leader.

A leadership struggle after today's elections now seems inevitable. It follows a surprise decision by the party's executive to drop its designation as 'unionist' and rebrand as 'other' in the Assembly.

The move left John McCallister – the second-in-command in Northern Ireland's newest political party – furious, and he publicly denounced the decision.

Last night party leader Basil McCrea said he had no immediate plans to meet Mr McCallister. Mr McCrea even suggested that it might be best if Mr McCallister did not remain in the moderate pro-Union party after he was the sole NI21 executive member to vote against the move.

The split at the top was reflected in social media online, as internal warfare erupted and council candidates took sides.

Annette Holden is Mr McCallister's PA and is standing in the Mournes. Yesterday she lambasted Mr McCrea on Facebook.

"Once the megalomaniac has been taken down, I truly believe we can rebuild this and continue the good work," she posted.

"McCrea should be finished before the weekend is out!"

Meanwhile, Balmoral candidate Barbara Neeson slammed Mr McCallister for "airing laundry in public". She wrote: "I side with the candidates who John didn't give a damn about with his interview."

Both Mr McCrea and Mr McCallister were elected as Ulster Unionists at Stormont. And when they quit to form NI21, the two MLAs kept their 'unionist' designation.

The controversy started after party chair and Euro candidate Tina McKenzie called an executive meeting at short notice on Tuesday to drop the 'unionist' designation in favour of the more neutral 'other'.

"It went to a vote which was overwhelmingly (in favour) if you count that there were five or six people in the room – Tina, Basil, Olive (Buckley), Stephen (Hillis) and Tony (McMahon), all voting for," Mr McCallister told the News Letter. "I voted against. I think it muddies the waters unnecessarily. I don't think it's helpful.

He added: "The way in which the executive was handled points to a lot of the dysfunctionality in the party. There was no agenda sent out... I was literally told to come down from my constituency to Belfast to do it, with no idea what it was about."

Mr McCrea defended the decision and hit out at Mr McCallister for opposing it so publicly on the eve of an election.

"For some people, being a unionist is their number one defining issue. If that is the case our structures and our framework may not suit those people. Obviously John McCallister and his colleagues might be in that category," he said. Friends say Mr McCallister had no intention of resigning and will fight his corner. He has received support from the party's youth wing and others.

Asked if he had been in contact with Mr McCallister to try and sort things out, Mr McCrea replied "no".

The row has been simmering for months and there have been several resignations. It is also understood Mr McCallister called in an outside body to assess allegations made against Mr McCrea.

This body is believed to be producing a report which could, eventually, lead to Mr McCrea's suspension under NI21's constitution. Last night Mr McCrea denied any wrongdoing and dismissed the allegations.

Belfast Telegraph