He is pushing reform in an institution that doesn't want to reform. He's pressing an agenda that few if any other countries are supporting. He's preaching to people who don't care what he thinks. Instead of confirming him, pull him out and don't replace him with anyone. Leave the position vacant. Make it clear to the UN what the U.S. thinks of it.
Better yet, get the UN out of the US, and the US out of the UN.