Tim Petrovic, Paul Claxton, Gene Sauers and Charles Raulerson share third at 10-under-par, while Bobby Gage and Tommy Biershenk are a shot back at 9-under.
Lebeck opened on the second nine at La Triomphe Country Club and birdied his first hole with a four-foot putt. He then carded a bogey at 13 when he landed his second on the edge of a bunker and could not get up and down.
He quickly regained the lost shot at the next hole when he drained a six-footer for birdie at 14. Lebeck missed the green short at No. 18 and failed to save par for a first nine of even-par 36.
Like his earlier bogey at 13, Lebeck rebounded at the next hole. He left himself a tap-in birdie at the par-5 1st and then added another birdie at the par-5 5th.
Lebeck drilled a 22-foot birdie at his last, the par-4 9th, to take a two-shot advantage heading into the third round.
'It's pretty hard to follow up a 61 with another 61,' said Lebeck, referring to his opening-round 18-hole record in this event. 'I am very happy that I shot 69. I wasn't expecting anything like the 61 but I was praying pretty hard last night that things would go okay today and that I could let myself have some fun and have a good number.'
Runge also played the second nine first and birdied three of his last five on the outward half for a 33. He added four more on his second nine for his flawless 65.
'It was a great day,' said Runge, who has missed the cut in both tournaments he started this year. 'I have been struggling a lot lately. This tournament, I played well last year and it seems to be carrying over to this year so I'm getting some good feelings going again.'
Casey Martin scored a bogey-free 68 on Friday and is in a tie for 11th at 7-under.
The 36-hole cut fell at 2-under-par 142 and 70 players qualified for the weekend.
Full-field scores from the Buy.Com Louisiana Open