Ed Miliband's reliance on trade union support to secure him the Labour leadership calls into question the legitimacy of his victory, a new report has claimed.
The leader of the Labour Party is chosen by an electoral college split equally three ways between Labour MPs and MEPs, party members and members of affiliated trade unions.
Three trade unions (GMB, Unison and Unite) had 75 per cent of the votes in the union section and each nominated and campaigned for Ed Miliband.
The report from the University of Bristol argues this meant the candidates did not have "equal and open access to the electorate" as the unions distributed ballots in a "partisan fashion".
Ed Miliband narrowly beat his brother David to the leadership in 2010. While David secured more votes from parliamentarians and party members, Ed had more support from the unions. In the end he won by a margin of only 0.65 per cent.
The report claims the unions unfairly "shaped campaigning" by restricting the availability of their membership lists to their nominee.
It notes that 49 per cent of voters followed their union’s recommendation when choosing who to vote for.
"The electorate was not fully informed; resources were not equalised; and ballots were not distributed in a neutral manner," it concludes.
His reliance on union support allowed opponents to dub him "Red Ed" following his victory last year.
It has been suggested that Miliband should aim to tackle the problem head-on by moving to cut union influence within the party.
The Guardian reported that he is planning to reduce their voting power at Labour's party conference in a fortnight. The plans are thought to involve unions having a smaller block vote in leadership elections.
The party is also heavily reliant on union funding with the latest figures showing of the £3.2m it received, £2.65m came from unions.