Thing is: the Tories are broadly aligned with the Republicans at the moment, and UK Labour are left of the Democrats, so you can toss the entirety of American politics by the same logic.
Just so I know: which democrats are openly arguing for embracement and increased funding for socialised medicine?
The Corbynista flank make the "Feel the Bern" people look like Reaganites.
Because there has not been an election with Starmer there is no manifesto to refer to, however there is this, which appears appropriate given your apparent focus upon the leadership.
https://keirstarmer.com/plans/10-pledges/