It will be the first opportunity to hear their visions for Scotland in detail, and it should be fascinating. I stress, should be.
Both candidates have already served up healthy dollops of anti-SNP rhetoric.
But whether either sounds convincing under scrutiny is a different matter.
As she has highlighted ad nauseam, Ms Truss has a decent personal story to tell.
The Foreign Secretary, who is the favourite to win the race, spent part of her childhood in Paisley, where she attended West Primary and lived in the affluent Castlehead neighbourhood.
She would be the first Tory prime minister since Alec Douglas-Home to have lived in Scotland.
Ms Truss considers herself a “child of the Union” and has promised to put it at the heart of everything her government does.
She recently sparked a (somewhat confected) row by calling Nicola Sturgeon an “attention-seeker” who is best ignored.
It was the kind of thing that might go down well with a certain kind of Tory voter, but doesn’t necessarily suggest a careful, considered approach to Scotland’s constitutional debate.
Besides, all politicians are attention-seekers, as Scottish Labour leader Anas Sarwar pointed out. As for whether they are best ignored, I’ll leave you to judge.
Mr Sunak branded the Foreign Secretary’s comments “dangerously complacent” and insisted the SNP “pose an existential threat to our cherished Union”.
He argues the Tories “can't just bury our heads in the sand and pretend they aren't there – we need to stop them in their tracks”.
Will the former chancellor be able to convince party members the Union is safer in his hands?
He secured some early, high-profile endorsements, but several MSPs have since swung behind Ms Truss.
Mr Sunak’s team say his plan to tackle the energy crisis focuses heavily on the role Scotland can play.
So that’s at least one vote up for grabs.