I think this is an overly ameri-centric take. There are a lot of factors impacting this war, and sure the composition of the US Congress is one of them, but it is fairly insignificant. A much bigger factor in deciding the war is how successful Russian mobilization is/was/will be, and the political costs to doing a partial mobilization. Another factor would be the sales of arms from Iran to Russia, and whether they can be used to real tactical effect beyond the terror-bombing we've seen thus far.