Delsing, who was one of five first-round leaders, completed 36 holes at 11- under-par 133.
Lee Williamson (64) and Jeremy Anderson (66) share second place at minus-10. Seven more players at tied for fourth at 9-under-par 135.
Delsing started on the back nine Friday and birdied the first two holes he played to move to minus-9.
He collected birdies on 15 and 18 to make the turn at 11 under. Delsing, a former member of the PGA TOUR, birdied the first before running into trouble.
Delsing tripped to back-to-back bogeys from the second at Somerby Golf Club to slide to minus-10. He got one stroke back with a birdie on the par-5 fourth.
The 46-year-old Delsing parred the final five holes to grab the 36-hole lead for the fifth time in his Nationwide Tour career.
'I know what I've got to do, I've got to get myself as low as I can,' Delsing admitted. 'There's still so much golf left. I just want to be the one leading on Sunday.'
Williamson dropped in birdies on the second and third, but gave both of those strokes back with a double-bogey on the fifth. He made the turn at minus-3 thanks to a birdie on the seventh.
The 27-year-old, who has missed the cut in four of his last six starts, caught fire around the turn. He eagled the par-5 11th and followed with a birdie on 12.
Williamson's lone mistake on the back came at the par-3 13th, where he stumbled to a bogey. He bounced right back with a birdie on 14 and an eagle on the short par-4 15th. Williamson closed with his third eagle of the back nine at the 18th to end in a share of second.
'I've never had three eagles in a competitive round,' stated Williamson. 'I'm not sure if I've ever had two.'
Anderson climbed the leaderboard with three birdies on the front nine, to turn in 7-under. After a birdie on 10, Anderson bogeyed No. 11. He posted three birdies over the final five holes to end at 10 under.
Chris Riley, a former American Ryder Cupper, carded a 4-under 68 to end in a share of fourth. He was joined at minus-9 by Chris Anderson, Richard Johnson, Tim O'Neal, Mark Brooks, Greg Chalmers and Esteban Toledo. Six players are one shot back at minus-8.
The cut line fell at 4-under-par 140 with 69 players moving on to the weekend. Among those missing the weekend were Carlos Franco, Jason Buha, former Masters champion Larry Mize and two-time PGA TOUR winner Len Mattiace.