Many characterize Putin's current position as taking as much territory as possible, while staying in the game long enough for US political climate to change. So I'd posit back, how would Putin's posture change if the US right was as aligned as the left on supporting Ukraine as long as it took? I suspect he would have taken a deal long ago.
Trump wants it to look as though he is the one making the deal happen, but the reality is he's the only reason it has not happened already. IMHO.