If Congress declares war, he will have to act as Commander in Chief whether he likes to or not. That ought to be interesting.
But he will lobby against war, and in the mean time there will be further incidents. The Muzzies smell blood in the water. So does China. He will have to respond to those incidents, and if he responds weakly, the incidents will escalate.
Only fools want war, but bigger fools try to avoid them with denial, foot dragging, vacillation, and obfuscation, and thereby create bigger wars. Once you have a war, it is best to fight it to win and finish it as fast as possible, preferably before your enemy is ready.
Nothing less than total war. Hit 'em fast, hit 'em hard.