Campbell, best remembered for losing in a playoff to Angel Cabrera at the 2009 Masters, shot a 3-under 67 in the second round at the Shaughnessy Golf & Country Club and was tied for first place with Michael Thompson.
Thompson, a tour rookie who has only one Top 10 finish to his credit, shot the tournament's low round to date, 66.
The co-leaders were at 4-under 136 for two rounds, one shot in front of Paul Goydos and two-time U.S. Open winner Lee Janzen.
Current Masters champion Charl Schwartzel, Geoff Ogilvy, Rickie Fowler, Jerry Kelly, David Hearn, Adam Hadwin and first-round leader Kris Blanks were all at 138 in a tie for fifth.
With the cut coming at 4-over 144, no player will begin the weekend more than eight shots out of the lead.
Luke Donald, the world's top-ranked player, survived the cut at 143 after missing the cut last week at the British Open.
Also making the cut was amateur Patrick Cantley at 143. Cantley was the low amateur at last month's U.S. Open and then shot a 60 the next week at the Travelers Championship to take the 36-hole lead. He eventually finished tied for 24th. Cantley has played in four professional tournaments this year and has made the cut in all of them.
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