The TUC advised them to join the white-collar union Apex, now part of the GMB.
"Red Ken", as he has long been known, has secured the nominations of major trades unions, such as Unite and the GMB.
His camp also has some hopes that the Scottish GMB might back him.
The GMB union, which represents Next shopfloor staff, said pay rises offered to Next staff would only put them 0.18p above the national minimum rate of £6.50 from 1 October.
The GMB union described the closure as devastating.
Three major unions - Unison, the Transport and General Workers and the GMB - will stage a rally in defence of public services, and will push for a vote on 'creeping privatisation'.The unions want to 'draw a line in the sand', demanding a restoration of the public-sector ethos.
Due to mergers, Unite, Unison and GMB represent three-quarters of the union section of the conference vote, making it very difficult for them to be defeated.
The GMB union let it be known amid hints of funding reviews that its general secretary, Paul Kenny, has written to Labour HQ calling the Balls-Miliband acceptance of a public pay freeze their "most serious mistake" yet.
Bert Schouwenburg International officer, GMB We might get Thatcher more nearly right if we stopped trying to treating her era as a seamless whole.
Paul Kenny, general secretary of the GMB union, said: "This is just the same old Tories who are anti-trade union, anti-working people having a voice and anti-democratic.
The GMB, representing more than 600,000 workers, accuses Mr Balls of peddling a "fake Tory argument" on cuts.But Mr Miliband and Mr Balls are moving in the right direction.
