DeWit previously was Arizona campaign chairman for Trump, who handily won Arizona's March 22 Republican presidential preference election.
Trump said “I have known and worked with Jeff for a long time and he is an outstanding leader and individual who will make it possible to for us together to win this election and make America great again.
"As one of the first public officials to endorse Mr. Trump, I am honored to be able to serve his presidential campaign and help him win in November," DeWit said in a written statement distributed by the Trump campaign.
"There is no question that he will make America great again."
