Campbell opened in 7-under-par 65 to tie Scott Peterson for the lead in the Wichita Open in Wichita, Kan.
Todd Rose is one shot off the lead after a 6-under-par 66.
Slocum, who has won two of his last three starts, shot a 1-over-par 73. One more win and Slocum will earn a 'battlefield promotion' to the PGA Tour.
Campbell - winner of the 2001 Richmond Open - recorded one eagle, six birdies and one bogey at the Crestview Country Club. His round included a 60-yard hole-out for birdie on the par-4 11th, a chip-in for birdie on the par-3 12th and a 35-foot eagle putt on the par-5 14th.
Hopefully, tomorrow I will come out and do a little better so it will be a little easier, said the 27-year-old Texan.
Peterson had a more routine round, one consisting of five birdies and an eagle.
I was telling one of the television guys that I put 12 new clubs into play today. Everything is new but my driver and 3-wood, said the 31-year-old Peterson.
Full-field scores from the Buy.Com Wichita Open