DES MOINES, Iowa (AP) — Like superintendents across the country, the leader of Iowa’s largest school system has faced plenty of criticism as he attempted to educate children in the past year while also keeping them safe during the coronavirus pandemic. But as pressure eases in many districts thanks to falling infection rates, Des Moines schools Superintendent Thomas Ahart is facing more uncertainty. Last week, Ahart had a contract extension rejected and this week he will argue that his license shouldn’t be revoked. For Ahart, the problems have been building for more than a year as his cautious approach that leaned on virtual learning contrasted with Iowa’s Republican governor’s push to reopen classrooms quickly.