If they don't secure that, it's a general election. But even if they do, they're only going to win by maybe one vote.
So. New Tory leader publicly abandons Theresa May's plod, and asks Europe to renegotiate. Europe says no.
Got to do a Queen's speech in the autumn, but half their own party is now ready to mutiny whatever they try.
New leader wins a vote of confidence, immediate panic over.
They know they can't pass a Queen's speech so they won't even try. Straight into a general election after summer.
Queen's speech passes.
The Brexiteers will be furious, and no one will care. There's a working cross-party majority for a referendum, so that's what we get.
But there will be a cross-party majority to prevent a vote of no confidence.
Tough. The new Tory leader is safe for at least a year.