Sir Keir Starmer is planning to relaunch his leadership of Labour in the autumn in a bid to prove the party is a credible option for voters at the next election.
In an interview with the Financial Times, Sir Keir said he would “turn the Labour Party inside out” to show it was serious about winning power and said members had to “get real” about damaging internal rows.
And he told the newspaper he had one goal: “To win the next election.”
Sir Keir’s leadership has been questioned by some on the left of the party since he took over from Jeremy Corbyn in April last year.
Factional disputes within the Labour Party have often been blamed for distracting from the task of opposing the Conservatives and have prompted multiple calls for unity.
But Sir Keir told the Financial Times: “We have to turn the Labour Party inside out and that’s what we’ve been doing for the last 18 months.”
He added: “Too many of our members and supporters think winning an internal argument in the Labour party is changing the world – it isn’t. We’ve got to get real.”
He said the party should be “very proud” of what was achieved under former prime ministers Tony Blair and Gordon Brown.
He said: “We have to be proud of that record in government and not be arm’s length or distant about it.”
Labour has lost the last four general elections and the 2019 result under Mr Corbyn was the party’s worst since 1935.
Fortunes appeared no better when the Tories took the former Labour heartland of Hartlepool in a by-election in May.
But supporters have been buoyed by the victory of Kim Leadbeater in Batley and Spen, in Yorkshire, in July.
Sir Keir told the Financial Times: “Under our current system if you want a Labour government you have to vote Labour.”