Just because there isn’t a vacancy, doesn’t mean there isn’t a contest. Although, until Theresa May’s shock decision to call a general election, most Labour MPs expected Jeremy Corbyn to lead the party into the next election, his would-be successors have all been quietly profiling for the top job. Think of it as the invisible Labour leadership contest.

The last few months have been exceptionally good for Yvette Cooper, partly because several of her rivals had bad ones. Dan Jarvis wrote a long essay that was largely poorly received in the parliamentary Labour party, and, to compound the error, called up one MP who criticised the piece on Twitter to complain.

Keir Starmer, regarded by many as the favourite in the next contest, whenever it comes, has had a poor few months thanks to his perceived mishandling of the Article 50 debate. His decision to welcome the government’s ersatz concession of a “vote on the final deal” caused consternation among MPs. (I explain in more detail why the government’s concession wasn’t worth anything here.) “Bewilderment at why Keir jumping up and down like he’d won the lottery,” said one former frontbencher summing up the mood among their colleagues. It added to two complaints that is increasingly widespread among MPs: that Starmer has “no politics”, and that having been elected just two years ago, he has yet to acquire the necessary experience.

Although his position among party activists was probably strengthened by quitting the shadow cabinet to vote against Article 50, in the short term, it has done considerable damage to Clive Lewis’ prospects of getting enough nominations to make it onto the ballot. He is no longer the natural first choice of most of the 14 MPs who gave Corbyn their nominations out of shared belief rather than to lent nominations. But he has no reach into the PLP’s centre, let alone its right flank. There is also a feeling in the PLP that Starmer’s struggles in the Brexit brief show that the candidate should not be someone who has “only been an MP for five minutes” in the words of another member of the 2015 intake.

It’s not only that Cooper has become the consensus choice in the PLP through the failure of others: she is also seen to have used the role of Home Affairs Committee Chair well, with a series of effective questions. She also put Theresa May under the cosh well during the liaison committee – when all the select committee chairs meet the Prime Minister – and has delivered two effective questions to May at PMQs. What one MP described as a "bravura" performance at the PLP meeting yesterday has further increased the buzz around her among MPs.

Her allies from last time are, for the most part, still behind her. One former Cabinet minister told me that “she has really decided to go for it now, and having had the last time to think about what she stands for, will be a much better candidate”.

But even less enthusiastic MPs, and opponents from last time around, are coming round. There is a strong feeling in the parliamentary party that whatever happens, Labour’s next leader must be a woman, and not just among the Women’s PLP. “I don’t think it’s time to talk about who the next leader is, whoever she may be,” one male MP said a few months back, “But it has to be a she, that I’m absolutely certain of.”

Others feel that what will be needed when Corbyn stands down is a safe pair of hands who will allow the various ginger groups – such as Labour Together and Red Shift – to continue developing ideas while a safe pair of hands steers Labour through tough times.

Another – a woman, but no natural supporter of Cooper – put it like this: “I think it needs to be first of all, a sister. Second, someone who has been around, and isn’t going to fuck things up. And third, someone who can unite the PLP. So that sort of leads to Yvette, I guess."

Some caveats: a lot of the rising support for Yvette Cooper has been based around the idea that Corbyn might stand down before an election in 2020. Corbynscepticism is a broad creed in the parliamentary Labour party and my guess is that, if and when Jeremy Corbyn departs the scene, its internal unity will collapse pretty quickly. Although the Labour membership is fluid, immigration remains an important issue to many members and one that Cooper is on the wrong side of. But here's the thing: that only matters if the next Labour leadership election is contested. At present, no other candidate is even getting close to Cooper's levels of support in the PLP. If there is a heavy defeat on 8 June, I wouldn't be shocked if the parliamentary Labour party gives the leadership to Yvette Cooper by acclamation, just as they did with Gordon Brown.