Shadow chancellor says he would also resign and calls for a woman to become new leader

Jeremy Corbyn would be likely to step down as Labour leader if the party loses the next election, John McDonnell has said, with the shadow chancellor adding that in such an event he would also probably quit his role.

In an interview with GQ, McDonnell also raised the possibility of Labour potentially supporting a second Brexit referendum before a general election, an idea popular with some Labour MPs but so far resisted by Corbyn and his team.

Speaking to Alastair Campbell, Tony Blair’s former spokesman, who was expelled from Labour in May for voting for the Liberal Democrats in the European elections, McDonnell said seeking an election first remained the official policy.

But he added: “I don’t think there is any doubt about a referendum. If it was a general election first or a referendum first, it doesn’t matter.”

Asked whether Corbyn could stay on if Labour lost the next election, McDonnell accepted this appeared unlikely.

“I can’t see ... I think it is the same for my own personal position, I can’t see so,” he said. “What we’d do is as the tradition, which is have an election for a new leader.

“I’m still of the view now that whoever comes after Jeremy has got to be a woman. We’ve got to have a woman leader. If you look at the new youngsters that have come through, they are fantastic.”

Corbyn has declined to say what he would do in such a situation. Asked previously whether he would stay on in the event of another election loss following a speech on Thursday, he did not respond to the question.

However, McDonnell insisted that Labour could win a majority, and responded to the fact he would be facing a different opponent this time with Boris Johnson as prime minister.

“I know that is true, but I also think he has got vulnerabilities just as much as Theresa May that we can expose and exploit in a campaign,” McDonnell said. “I’m not being unrealistic, but the political climate is incredibly unpredictable. You can’t use the usual gauge sticks.”

The shadow chancellor said that if Labour did not win an outright majority but ended up the biggest party, they would not enter a formal coalition with the SNP or Liberal Democrats.

“Well, I think we can win a majority, but if we go into a minority government situation, there will be no deals, we’ll just lay out our programme and they either support it or they don’t,” he said.

“If they don’t support it we’ll go back to the country and it will be interesting, if they did, to see how they argue against a real living wage, investment in public services, restoration of trade union rights, tackling climate change. How can they argue against that?”

On the choreography of whether a referendum should precede an election, McDonnell acknowledged the differences of opinion.

“I’m more of the view that we’ve said up until now that we want a general election. That, of course, is what our objective is, but let’s see what actually parliament will wear in the end,” he said. “Within parliament itself there is a large number of people who are saying we’d rather have a referendum attached to any deal.”

Asked what order he would prefer, McDonnell said: “I want a general election, actually. I would like a general election.”

McDonnell, – who told Campbell he did not support his expulsion from Labour and would welcome him back – said Johnson’s approach to politics risked encouraging dangerously populist sentiments.

“I don’t think Johnson has much of a belief at all. I think this is the ruthless pursuit of power for power’s sake,” he said.

“That is why I caution him to be careful with what he’s unleashing here. What has happened in the past when these rightwing forces have been unleashed is that you’ve got a politician for who, literally, truth doesn’t matter to. Secondly, they start attacking the institutions that protect our democracy – parliament, judges, the rule of law.

“Once you get into that territory, you’re into danger territory and you don’t know again how that will wind up and I think there are real issues there and lessons we’ve got to learn.”