First-round leader Craig Perks struggled to a 1-over 71. He shares third place with Steve Flesch, Robert Gamez and Jeff Maggert at 5-under-par 135. Stewart Cink, Lee Janzen and Zach Johnson are one stroke further back at minus-4.
Leonard began the day at even-par, six shots behind Perks. Leonard got off to a fast start with birdies at the first and third.
The University of Texas alum cruised to three straight pars before dropping in back-to-back birdies from the seventh at Colonial Country Club.
Leonard moved to 5 under when he chipped in for birdie at the par-4 10th. The former British Open champion nearly holed his second shot to the par-5 11th. He calmly rolled home his 7-foot eagle putt to jump into first place at minus-7.
Leonard, whose last win came at the 2003 Honda Classic, lost his momentum though. He faltered to consecutive bogeys from the 12th to slide back to 5 under.
'Unfortunately, at 12, I didn't hit a very good tee shot and played safe on my second shot and three-putted for bogey,' Leonard said. 'On 13, I tried to play safe again and hit it just a little too far and ran my chip past the hole. That was disappointing, a little bit deflating.'
He re-claimed a share of the lead when he dropped in a 25-foot birdie putt at the par-3 16th.
'I've been struggling the last couple of months and showing signs of playing well at times, so to go out and shoot a round today like I did, it feels very good,' said Leonard. 'Hopefully this is the beginning of some good play.'
Lewis was steady throughout his round. He carded one birdie on the front nine, at the par-4 sixth, and eight pars. Around the turn, he climbed to 4 under with a birdie at the par-4 10th.
The two-time winner on the PGA Tour converted back-to-back birdies from the 14th to climb into first place. He was parred in before Leonard later joined him in first place.
Masters champion Phil Mickelson heads a group of players at 3-under-par 137. He is joined there by Jesper Parnevik, Dennis Paulson, Tom Byrum, Brian Gay, Tim Petrovic and Bo Van Pelt.
Defending champion Kenny Perry is among a group of 11 players at 2-under-par 138.
Carl Pettersson ran off three straight birdies from the 15th to erased two earlier bogeys. Around the turn, he eagled the first to get to minus-6 and a share of the lead.
Things went downhill from there for the Swede. He bogeyed the fourth and double-bogeyed the sixth and stumbled to back-to-back bogeys from the seventh before closing with a double bogey to finish at 1-over-par 141 after a 74.
The cut line fell at 3-over-par 143 with 74 players advancing to the weekend. Among those missing the cut were Stuart Appleby (144), John Huston (145), Shigeki Maruyama (145) and Billy Mayfair (146).