I'm an American living in Russia and it never fails to amaze me how the West completely underestimates the truly huge support for Putin at all levels of Russian society, from the grass roots of ordinary people to the professional elite and upper middle class and to the truly powerful. A large majority admiring Putin is one of the genuinely unifying phenomena in Russia that crosses ethnicity, age, and educational and economic status.

So it's extremely difficult to come up with scenarios where such mass approval of Putin could be reversed and thus result in somebody else being elected instead of him to lead the country. But one such scenario would be Putin capitulating to the US and allowing the Ukraine conflict to freeze in a way that leaves nazi Ukraine intact as a military power and threat to Russia. The Russians I know would find that unthinkable, but if Putin did it I think he'd go from hero to zero that same day.

It would still take a long time for the displeasure people would have at him to manifest itself - there's a lot of inertia built into the Russian system, partially as a protection against Western-style superficiality. A six year presidential term is a long time to bear an unpopular leader, as Macron keeps demonstrating. But I believe the next election cycle starting with local and regional elections would see the end of any candidates who did not take a hard line position against the capitulation.

I don't think any Soviet style electoral shenanigans (which have been absent for decades, but people liking their sinecures might be tempted to reach for tools remembered from Soviet times) would work, because veterans who felt betrayed would be muscle to be reckoned with, and they'd be solidly on the side of booting capitulators out the door, if not stringing them up on the nearest tree.