Image copyright Reuters Image caption Although many Labour MPs question Mr Corbyn's electability, his mandate is still strong

"I'm here - I'm going on." No political leader wants to have to answer questions about their leadership, to defend their own position.

The behaviour of one of his old friends in the last few days has put Jeremy Corbyn on the back foot again, struggling to contain a restive party, struggling too to persuade his party to focus only on elections in which he, for the first time, will be subject to the judgement of voters in every corner of the country.

The papers are full of stories of plotting MPs, stalking horses, and moves to remove him from his perch. So how on earth can he be so sure he will be "going on"?

Well, he can't be completely sure. No politician ever can. The last few days for Labour have been among the most bloody since he took over in September. Most Labour MPs think that the chances of him ever walking through Downing Street's shiny black door as prime minister are negligible.

And there are a handful of MPs who think that it would be best to get the pain of unseating him out of the way as soon as possible. Like tearing off a plaster, it's better to do it quickly, howl with pain, and then the real healing process can begin.

Certainly, concerns over anti-Semitism in some strands of Labour have been profound. After rumbling on for some time, that concern exploded into outrage as Ken Livingstone proved himself incapable of stopping digging.

Don't get me wrong, it has been a mess, some voters are deeply offended, the relationship between the Labour Party and the Jewish community has without doubt been seriously damaged. But, take a deep breath - the fundamentals that have kept Mr Corbyn in his job since September have not changed significantly, yet.

Image copyright EPA Image caption The EU vote result will have a bearing on both Jeremy Corbyn and David Cameron's fortunes

Mr Corbyn's unprecedented mandate from invigorated Labour members is more or less intact, even if it is starting to fray around the edges. And the MPs who want him gone can't agree yet on a candidate to take over, or indeed, a set of ideas that could compete with Mr Corbyn's set of principles that persuaded the party membership who choose the leader that he was the right man for the job.

And even if there was, there is precious little support for acting against Mr Corbyn until after the European referendum on 23 June, the biggest political decision in a generation.

But the referendum doesn't just make it harder for Labour plotters to move. The referendum result and how the Tories react to it could be the biggest factor in determining whether his enemies ever move to take him out. Sound strange? Bear with me.

Snap election?

While David Cameron and his senior colleagues deny he'd have to go, there are plenty of influential Tory MPs who believe behind the scenes that he won't last long at all if he loses the referendum. And even if Remain wins the day, if the result is close, the prime minister's position could feel shaky. Why do the Conservatives ongoing euro-spats have a bearing on the Labour leadership?

There is a view emerging, that if the referendum results in so much of a whiff of a Tory leadership challenge, or a hastening of David Cameron's departure date, then the chances of a challenge to Mr Corbyn plunge.

That's because a change of Conservative leadership could result in a general election before too long. The appeal of that to some Labour politicians who want to see Jeremy Corbyn gone is simple. If MPs act against him the results could be messy, traumatic, and turn the membership against them.

What would be cleaner, and more democratic to boot? Why, of course, rely on the general public's judgement about the party under his leadership at a general election, that they believe could remove him fairly and squarely.

Are there really Labour politicians hoping for an early general election that could see them lose again? They'd probably describe themselves as pragmatists looking at the prospects for their party, but in short, yes there are.

As ever, political predictions should always come with big caveats. There are many 'ifs' with a capital 'I' in the above scenario.

There are also many competing theories about the best way of either keeping Mr Corbyn in charge or removing him. And of course his allies want to do everything in their power to keep him in. This strategy is far from a settled plan.

But however bad it gets for Mr Corbyn - and his own prediction that the party won't lose any seats in Thursday's elections probably won't have helped his cause - an uncertain referendum result might mean a general election before too long.

And that could be the biggest factor in protecting him from a potential internal putsch, even if that may not be what is on his mind when he says "I'm going on" .