CHUKA UMUNNA broke ranks with fellow Blairites yesterday by calling on colleagues to rally around the new Labour leader — even if it turns out to be Jeremy Corbyn.

The shadow business secretary is backing Liz Kendall in the contest, who has said she would refuse to serve in Mr Corbyn’s shadow cabinet.

And he expressed “grave” concerns over some of the left-wing candidate’s proposals, such as renationalising some industries and pulling Britain out of Nato.

But with Mr Corbyn now the firm favourite to be named leader on September 12, Mr Umunna sought to build bridges between the party’s warring factions.

Speaking on Radio 4, he did not rule out serving under Mr Corbyn and said: “I am very clear that whoever is the winner we’ve all got to get behind.”

The interview followed a speech he gave on Tuesday evening in which he said: “Solidarity is key, which is why we must accept the result of our contest.”

Mr Umunna also distanced himself from a potential right-wing challenge to the election result over claims of infiltration, saying the huge numbers of new supporters were “surely something to celebrate.”

However, he and other MPs have formed Common Good, a pressure group established in anticipation of Mr Corbyn’s victory, which has been dubbed “the resistance.”

Many social media users expressed cynicism about the motivation for his surprise unity call, believing that it had more to do with his own career prospects than true conviction.

Yasir Yusaf wrote: “Here we have a clear example of a human pancake #flipflop.”

Labrokes responded by slashing the odds on Mr Umunna becoming shadow chancellor from 33/1 to 5/1.