Jeremy C and Boris J have a big thing in common - well almost - in part because of their roles in the referendum.
Many Labour MPs want Corbyn replaced as leader.
And substantial numbers of Tory MPs want to stop Johnson replacing Cameron as leader.
The view among Labour MPs, who didn't want Corbyn in the first place, is that his campaigning weaknesses were a big reason why Remain lost.
Many of them also think he lacks the experience and expertise to position Labour during complicated Brexit negotiations and to see off the challenge for their working class vote from UKIP.
There is therefore an attempt to build a consensus for a single credible challenger to Corbyn - because it is thought he could not possibly be ousted unless the parliamentary party were to unite around a single rival candidate.
There are three names in the frame: Tom Watson, Angela Eagle and Yvette Cooper.
And it is widely thought that as deputy leader, it is down to Watson to initially decide whether he is up for it, or whether he thinks Eagle or Cooper would be better placed to win over the membership and unite the party.
All is expected to be sorted in coming days.
As for Johnson, the idea that he is a shoo-in to replace Cameron is quite wrong.
Many of his fellow Leavers don't believe he is really one of them.
And perhaps the majority of Tory MPs who went for Remain will never forgive him for what they see as his grotesque disloyalty to the prime minister - and the vitriol he employed against them.
So the big game in the Conservative Party is Stop Boris.
Which isn't easy, in a system where the ultimate decision on who becomes Conservative leader rests with Tory members - and they almost universally love him.
The leadership election system involves Tory members choosing between two candidates who have themselves been selected by the MPs. So the MPs either have to find two candidates they like more than Boris, or they have to somehow dissuade him from running.
Who might MPs actually prefer?
Well Gove has said he won't run.
Theresa May is regarded as impressive, but isn't much loved.
And George Osborne knows he killed his leadership prospects with his aggressive campaign that Leaving the EU would be to make us all poorer (he may be right - but that's obviously just a detail).
Or to put it another way, Osborne sacrificed his career to save his friend David Cameron and for the European cause - which comes with a painful irony for him, because he was a rare senior Tory who tried passionately to dissuade David Cameron from holding the referendum in the first place.
So who might Tory MPs and members coalesce around as the anyone-but-Boris leader?
Well as my colleague Chris Ship rightly pointed out, there's growing towards the anointment of the young Work and Pensions secretary Stephen Crabb - whose working class background and impeccable manners recommend him to many.
But the thing is Crabb has only been in a big cabinet job for a few weeks. And it is quite a leap from Work and Pensions to 10 Downing Street.
And that's an issue for him and for the electorate.
Will it be Crabb?
You know, it might just.
And is Osborne totally finished? That I doubt.
Here's a counter-intuitive thought from a shrewd political player.
Someone is going to have to negotiate the UK's extrication from the EU, and no one in the Tory Party has Osborne's technical expertise.
So if Osborne can't be leader, at least this time, he would be the rational choice for foreign secretary of whoever comes after Cameron.