Career
O'Brien is a lifelong resident of the Mahoning Valley and graduate from John F. Kennedy High School as well as Youngstown State University. O'Brien served on Warren City Council from 1983 to 1993 before being elected as a Trumbull County Commissioner in 1994. He served as a commissioner for ten years before being elected Mayor of Warren in 2005, serving until 2012.
O'Brien announced in early 2014 that he would seek a seat in the Ohio House of Representatives to replace Tom Letson who was term-limited. He faced former Republican state Representative Randy Law in the general election, in what became a very tight race. He defeated Law 49%-44% to take the seat.
