A new Tory leader can't be certain of becoming prime minister, Robert Peston writes

Call me old fashioned, but I find it impossible to see how any Tory leader could survive crashing to fifth place in a national election and picking up just 7% of the vote - which is what YouGov predicts in the Times.

Of course it's only one survey. The real vote tomorrow may yield a better outcome. And Labour is also set for a humiliating night, with just 13% of votes cast, say the pollsters.

But 7% for the supposedly natural party of government, for just the past couple of centuries, is the kind of humiliation that few institutions would shrug off. May should count herself very fortunate she isn't a football manager, because she'd have been back managing Port Vale some time ago.

I am of course talking only about the timing of her departure, not the inevitability of it. The moot question is whether she will quit next week. Her great defender, Michael Gove, said probably not. Rancorous Tory MPs tell me she must.

Voters will head to the polls on Thursday to vote in European elections. Credit: PA

I should mention, because these things seem to matter to prime ministers, if May were to announce her intention to go on Wednesday, she would have remained in office a day longer than Gordon Brown (I think).

What is striking however is the absolutely yawning gap between our MPs and the people of Britain about what really matters.

For voters, the European Parliamentary Elections appear to show it is all about Brexit.

YouGov shows backing for a hard or no-deal Brexit at 40% via intentions to vote for the Brexit Party (a staggering 37%) and UKIP.

Whereas support for a referendum would ALSO be 40%, aggregating the support for LibDems, Greens, SNP, Plaid Cymru and Change UK.

When the Brexit or no-Brexit future of our country is at stake, the perceived ambivalence of Tories and Labour on the only question deemed to matter has seen the two major parties placed in the dustbin of irrelevance.

Which carries an unmissable implication - which is that the revival of each party requires the Tory Party to become the party of a harder or no-deal Brexit under a "proper" Brexiter leader - likely to be Boris Johnson - and Labour to become the party of a confirmatory referendum.

That in turn means there are only two democratic routes to sorting our Brexit or no-Brexit future, which is either via a referendum or a general election.

Nigel Farage's Brexit Party is expected to perform well at the elections. Credit: PA

Now it is by no means certain that if Johnson were elected Tory leader on a platform of a more abrupt rupture from the EU, he could command a majority in the House of Commons - since some of his MPs on the pro-EU left of his party would resign the whip (Grieve, Lee, Johnson, Vaizey and Gyamah spring to mind, inter alia).

If Johnson bowled up at the palace and told HM he wanted to form a Government, HM could reasonably query whether he has the votes.

He could attempt to hold his party together by offering a referendum, but that would presumably see his Brexiter wing brand him a traitor and refuse to support him were Labour to call a confidence vote.

So as I've said to you many times before, a general election looks unavoidable, probably in the autumn. And the big question for the Tory Party is whether it would fight Farage's Brexit Party as the enemy or embrace a pact with him and it.