Chip Beck, playing in his third Champions Tour event, fired a 7-under 65 and is tied for second place with overnight co-leader Loren Roberts, who shot a four-under 68. The pair is knotted at minus-9.
Mitch Adcock, a sponsor's exemption who was tied with Roberts after Friday's first round, managed a 3-under 69 and is alone in fourth place at 8-under-par 136.
Jenkins began the second round one shot behind the first-round co-leaders and did not make up much ground early. He parred his first four holes, but drew closer with back-to-back birdies at five and six.
Adcock moved one ahead with a 7-foot birdie putt at the ninth, but Jenkins matched him in first with a long birdie putt at the 10th. Adcock once again forged ahead with a 12-footer for birdie at 12, but things changed at the 13th.
Jenkins rolled in a 17-foot birdie putt at 13, while Adcock made a mess of the hole en route to a bogey. Jenkins was now one ahead, but Roberts was making a move.
Roberts, the tour's leading money winner, only trailed by a shot thanks to birdies at seven and 12. At the 14th, Jenkins got up and down for par from 88 feet, while Roberts, nicknamed 'The Boss of the Moss,' missed a 13-footer for birdie.
Both Roberts and Jenkins birdied the 15th and 17th holes. Jenkins' 17-footer at 17 boosted him to 10-under par. Jenkins had 31 feet for birdie at the last, but two-putted for par. Roberts again had a makable birdie try from 13 feet at the last, but missed.
'I had a lot of chances on the back nine,' admitted Roberts. 'I hit every fairway and every green. I'm looking for some good things tomorrow. I like the way I'm playing now.'
While two of the members of the final group were duking it out, Beck steadily climbed up the board. He birdied three and four, but it was his play on the back nine that vaulted him into contention.
He ran home a 9-foot birdie putt at 12, then parred his next two. From there, Beck collected four consecutive birdies to close his round, including a 6-footer at the last.
'It's a big horse race here,' said Beck, looking for his first win since 1992. 'I'm just so thankful to have the opportunity to play golf again. It's like heaven on earth.'
Before Beck reaches nirvana, he'll have to get through Jenkins, a six-time winner on the Champions Tour, who last visited the winner's circle at the 2005 Allianz Championship.
'I've hit some good irons this week and I'm putting well. I'm seeing the line well' said Jenkins. 'It's gratifying to play a round without a bogey.'
Jay Haas, second to Roberts on the tour's money list, carded a 6-under 66 and is alone in fifth place at 7-under-par 137. Last week's winner Andy Bean (69) and Jim Ahern (70) are tied for sixth place at minus-5.
Raymond Floyd (69), Gil Morgan (69), two-time winner this year Brad Bryant (71) and in his second tournament on the elder circuit, Scott Hoch (71), share eighth at 4-under-par 140.