Sen. Sherrod Brown (D-Ohio) is out with his first ad of the 2012 reelection campaign, going after his opponent, State Treasurer Josh Mandel (R), on charges of cronyism.Mandel has been under scrutiny for installing inexperienced staffers in high-ranking government jobs, despite a 2010 campaign promise to ensure the state treasurer's office would be "comprised of qualified financial professionals -- rather than political cronies and friends."One of the hires Brown's ad mentions is Joe Aquilino, Mandel's debt management director, who attended a beginner's course in the subject he was overseeing.