SAN FRANCISCO — As the debate about splitting the U.S. Court of Appeals for the Ninth Circuit continues to gather steam, President Donald Trump announced his first nominee to the court, which has been something of a thorn in his side.

Trump nominated Ryan Bounds, an assistant U.S. attorney in Portland, Oregon, and former clerk for Judge Diarmuid O’Scannlain of the U.S. Court of Appeals for the Ninth Circuit, Thursday morning to fill the seat left open when O’Scannlain took senior status at the end of last year.