Would they try to kill him?

The "powers that be" is the spirit that rules this world. It is Satan, the deceiver of the whole world. And, yes, he has great influence upon men of the world, which means all (Jews, Gentile, and everyone else). If the Messiah or the Christ or the Anointed One should show his face in the world, no doubt the people would run him out of town on a rail or tar and feather him.