But this discussion isn't about grassroots or local politicians. Following the logic espoused in the OP you'd turn out in droves to vote for a local politician who offers policies you agree with.

This discussion is about the presidential election and what to do about two candidates who both actively support genocide.

One could conceivably not vote for Kamala and then massively support your local grassroots movement and politicians, or... You could vote for Kamala and then massively support your local grassroots movement and politicians.

Talking about whether or not to vote for Kamala has no bearing on what you then do at a local level.

And if that local-level politician doesn't offer policies you like, same logic. Why would they ever do so if they're guaranteed your vote anyway?

What's at stake here is people actively arguing that we should just guarantee one political party our votes, no matter what their policies are, out of blind faith.

That's not a democracy, it's a theocracy.

if that “guaranteed” base grows, it provides a voting offset that could allow the candidate to worry less about losing the support of less progressive voters.

Sure.

But why would they? If the base that's 'grown' is guaranteed, then why shift at all? Why not have the new larger guaranteed base, and the less progressive voters. After all, the guaranteed base is guaranteed, you don't need to do anything to get their votes.

But let's say they want to risk it for ideological reasons (no evidence at all that this is the case, but for the sake of argument we could assume it).

You've still not addressed the two main questions.

1. How do they know the extra votes came from left-leaning but 'guaranteed' voters, and not from voters who really liked their centrist policies?

2. If they have some way of knowing (polls, focus-groups etc) then why can't they use that way of knowing to ask about voter commitment, and make the move to the left before the election, why do they need us to actually vote first to find out if we're in this 'guaranteed base'?

Oh. I've just looked up 'sea-lion'. Jesus fucking Christ. In one thread we've had the argument, from supposed progressives, that;

1. Vote your government back in no matter what their policies are, just do so out of blind faith.
2. Don't look things up for yourself, just accept what the authorities tell you without question.
3. Don't ask for evidence or challenge this view, just accept it without question.

This is the progressive position now?

This isn't politics, it's a fucking religion.