He ran on it, and he won big on it
"If we're going to raise revenues that are sufficient to balance with the very tough cuts that we've already made and the further reforms in entitlements that I’m prepared to make, then we’re going to have to see the rates on the top two percent go up. And we're not going to be able to get a deal without it. It's not me being stubborn -- it's not me being partisan. It’s just a matter of math."
And since over 60% of the country wants it, he'll get it.