Michael Clark II posted a 7-under 65 to join Geoff Ogilvy in a tie for second at 11-under-par 133. Carlos Franco also stands 11 under through 13 holes.
Play was called when rain rolled through the Tucson area. The second round is scheduled to resume Saturday at 9:45 a.m. ET.
Slocum, who held the 54-hole lead at this event in 2002 before finishing four shots off the pace, took advantage of his early tee time at Omni Tucson National to surge to the top of the leaderboard.
'I think that I play very well in and around the lead,' said Slocum. 'I've also played poorly, but I would love another opportunity to make this week my week.'
He started on the 10th and landed his second shot inside 40 feet at the par-5 hole. Slocum two-putted for the opening birdie and added another at the par-4 14th after his approach stopped 10 feet from the hole.
Slocum continued his fine play with a birdie at the 16th and hit a 6-iron within 12 feet of the cup at the par-4 18th. He drained the putt to make the turn at 9 under and begin a little bit of a streak.
The 30-year-old ran home a 25-foot putt for a birdie at the first and reached the green in two at the par-five second. Slocum then took two putts for his third consecutive birdie.
At the par-4 fifth, Slocum knocked a wedge to eight feet and converted the birdie try. Slocum then missed the green at the par-5 eighth but chipped his third shot to four feet for his eighth birdie of the day.
'I drove it well, I hit a lot of greens again today,' said Slocum, who has gone bogey-free through the first two rounds. 'I had a couple, maybe four- or five-footers for par. But other than that, everything else was pretty solid all day.'
Franco also played the back side first and opened his round with a bang at the par-5 10th. Franco hit his second shot inside 30 feet and drained the putt for an eagle. He added two birdies to move within two of the lead before play was halted.
Per-Ulrik Johansson, Tim Clark and Vaughn Taylor are knotted at 10-under-par 134. Harrison Frazar was at 10 under par through 10 holes before the bad weather arrived.
Defending champion Frank Lickliter II, who held the opening-round lead after a blistering 63 on Thursday, struggled to a round of 73 to finish at 8-under-par 136.