The Labour leader is seeking to change the party’s leadership rules, reducing the power of members and boosting that of MPs and trade unions. Sir Keir wants to return to Labour’s old system; under which MPs, party members and trade union representatives had a third of the vote each for leadership elections.
This was abolished by Ed Miliband in 2014, who instead gave one vote to each Labour, and affiliated trade union, member.
Jeremy Corbyn was elected as Labour leader under this system in 2015, securing over half the vote despite little support from MPs.
Allies of Mr Corbyn fear the proposed rule changes, are designed to make it harder for the Labour left to win another leadership election.
Ms Abbott, formerly the shadow home secretary, hit out at Sir Keir on Twitter.
She tweeted: “When will it occur to Keir Starmer that the ludicrously undemocratic electoral college that he is trying to force through, will not just make it easier to block left wing Labour Party leaders, it will make it easier for the right to dump him when the time comes?
“Keir Starmer would NEVER have got elected leader if Labour Party members had realised that he planned to take power away from them by scrapping one person one vote.
“If he is successful in scrapping one person one vote for leadership elections, Keir Starmer is in effect telling party members that they can never have a leader who believes in the things that they believe in.
“When Keir Starmer was campaigning for the Labour leadership he promised ‘common ownership of rail, mail, energy and water’, and a crackdown on corporate tax avoidance.
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He is reported to have said: “These rules won’t be presented on a take-it-or-leave-it basis.
“I am prepared to take suggestions and ideas and have a conversation and to try and build consensus. But the principles are important to me.
“I hope [the trade unions] will support me. I believe these changes are good for their members and they strengthen our link.
“I know that this is difficult – change always is – but I think these changes are vital for our party’s future.”
The proposals have been sharply condemned by Momentum, a left-wing group formed to support Mr Corbyn’s leadership.
They warned: “Any attempt to take these rule changes to conference would mark the start of a civil war in the party.
“Grassroots members will have no choice but to mobilise all our strength to fight back against this bureaucratic attack.
“Conference will get very messy, very fast – and there is no saying who will come out on top.
“This marks a new low in Starmer’s leadership.”
Mr Corbyn was suspended from Labour last October over his reaction to a report on anti-Semitism within the party.
Whilst his Labour membership was swiftly restored, he still hasn’t regained the Labour whip in Parliament.