Trump despises the 9th Circuit Court of Appeals; why doesn’t he change it?

Erwin Chemerinsky quoted by McClatchyDC.com, Jan. 16, 2018

“Trump is going to have an enormous effect on the 9th Circuit,” said Erwin Chemerinsky. … “Trump right now can fill about 20 percent of the seats on the court, and he still has at least three years left in his term. He could dramatically alter the composition of the court.”