Unite union chief rounds on Miliband

The head of Britain's biggest union tore into Ed Miliband last night, warning that the Labour leader was taking the party to disaster – and risking his own survival – by alienating its most loyal supporters.

Len McCluskey, the general secretary of Unite, attacked the announcement by the Shadow Chancellor Ed Balls that Labour would support the cap on public-sector pay and could not promise to reverse Coalition spending cuts. Writing in The Guardian, he said Mr Balls' "sudden weekend embrace of austerity" was "a victory for discredited Blairism at the expense of the party's core supporters". He added: "It also challenges the whole course Ed Miliband has set for the party, and perhaps his leadership itself."

Mr McCluskey protested that, with Labour backing the Coalition on the issue, there was now a consensus among the "political élite" that disenfranchised opponents of austerity measures.

His comments will send a chill through the Labour high command as Unite is the party's single largest donor and provided crucial backing to Mr Miliband's leadership campaign.

Amid criticism of his performance and dismay over lacklustre opinion poll ratings, Mr Miliband reassured 150 of the his MPs and peers that he had "the stomach for the fight".

But he warned there were more "tough choices" to be made over spending after Mr Balls' decision. Every shadow Cabinet member would be looking at their own portfolios to establish where savings could be made, he told the Parliamentary Labour Party.