Swafford rolled in three birdie putts on each nine and kept a bogey off his card to return a 66 and take the clubhouse lead on 11 under par, while first-round leader Boo Weekley was on the same score with three holes to play when the players were called in.
Veteran Weekley, chasing his fourth PGA Tour title and his first since May 2013, was also bogey-free through 15 completed holes in an excellent follow-up to his sparkling, opening 64.
Swafford, who has recorded just one top-10 in 16 starts this season, is delighted that changes to both his swing and his putting stroke have reaped rewards this week.
“Nothing was really clicking for me so I kind of changed the takeaway with my golf swing, and actually my stroke with the putter,” he said.
“I’ve been trying to bring it a little more inside and down the line. Ever since then, Bay Hill, it has kind of kicked in and I’ve really seen some good golf.”
The top two hold a one-shot lead over a group of five players including world No 6 Jason Day, who carded three straight birdies around the turn and had just made his fifth birdie of a flawless round at the 14th before the suspension.
Brendon de Jonge (70) and Cameron Tringale (65) are in the clubhouse at 10 under, while the evergreen Jerry Kelly reeled off four consecutive birdies from the 13th and was eight under for the round with just the par-five 18th to complete when play resumes at 8am on Saturday morning.
Daniel Berger, runner-up to Padraig Harrington at the Honda Classic earlier this season, also joined the share of third place with three holes remaining, while former American Ryder Cup star Chad Campbell headed a group of six players on nine under par.
Seven more players were at eight under including Australian Marc Leishman, who is making his first start since being forced to pull out of the Masters while his wife recovered from serious illness.
Leishman made four birdies on the front nine and then put together a stunning run of six birdies in seven holes to reach 10 under for the round, although he faces a 30-foot putt for par at 18 on Saturday morning after pushing his second into water.
English journeyman Greg Owen is also among the group at eight under, while Justin Rose is four under for the round and seven under overall with three holes to complete.