There were just 10 rounds in the 60s on Thursday and only 23 players broke par.
One of those breaking par was John Daly, the two-time major championship winner whose career has deteriorated in recent years due to off-course problems. This is only his second appearance on the PGA Tour in 2012 and he has just one Top 10 finish on the circuit since 2005.
Daly shot a 1-under 70 in a round that included three birdies.
World No. 1 Luke Donald, who suffered through a disappointing Masters last week, shot a 75 and found himself in danger of missing the 36-hole cut. Newly-crowned Masters champion Bubba Watson is not playing this week.
Campbell lost in a playoff at the Masters to Angel Cabrera in 2009 and since then has had only three Top 10 finishes. He has missed the cut in five of his nine previous starts this year.