There's no negotiation needed. Russia moving out of Ukraine and paying for all damage until everything is pre crimea. If that is all done, rebuild and paid for, then, they can negotiate for less punishment on top. That's the kind of negotiation you start because both sides have something to gain and not one to keep his unjustified war territory.
There's a pretty good chance they won't be able to keep this up for another year. Ukraine is running out of manpower, and NATO lacks the industrial base to supply weapons at the rate they're used now that existing stocks are running dry.
On top of that, US is now getting sucked into a war in Western Asia.
I could see it being over by December no matter which candidate wins, especially if Israel succeeds in starting WWIII by enticing the US into direct conflict with... basically all its neighbors? 👀
Even if there is no punishment on top, if Putin ends up losing all he gained, heads will roll including Putin's. If he can gain any amount of land in a negotiation and end the war, he can go back to his people and say that it was all worth it and many of them will buy it.