"I'd say it's pretty close right now," O'Brien said in an interview on ESPN Radio's "Mike and Mike" show. "I'd say by the end of the week we'll probably make a decision. But whatever we do we'll do what's best for the team. We have two really talented guys there."
This year's starter will replace Matt McGloin, who rewrote the school record book in O'Brien's first year on the Penn State sideline, completing 60.5 percent of his passes for 3,271 yards with 24 touchdowns and five interceptions.
O'Brien praised Ferguson and Hackenberg, calling them two of the best young quarterbacks he's ever coached.
"These guys have come into training camp and really have had good command in the huddle," O'Brien said. "They've got a decent grasp of our offense. They're throwing the ball well."