Turner and Barrett, each looking for their first victory since 1989, started the round a shot off the pace and got to 9-under 135 at the Rail Golf Club.
Barrett opened with a chip-in eagle from about 110 yards at the first hole, and followed with three birdies and two bogeys. Turner carded six birdies and overcame a double-bogey after hitting her tee shot at No. 16 into the water for the second straight day.
``I don't know what the deal is ... I told my caddie, 'Tomorrow, you line me up,''' said Turner, who is seeking her fourth LPGA Tour win.
First-round leader Heather Bowie had a 1-under 71 and was one stroke back at 8 under along with Maria Hjorth, Liselotte Neumann and Pat Hurst.
Neumann, a 13-time winner, had a second-round 7-under 65, while two-time winner Hjorth carded a 5-under 67. Hurst had an inconsistent round of eight birdies, two double-bogeys and a bogey in a 3-under 69.
``I can't think about that. It's over and done with. I got the birdies and will carry that into Saturday and Sunday,'' said Hurst, a three-time winner and a member of the U.S. Solheim Cup team that faces the Europeans on Sept. 9-11 in Carmel, Ind.
Natalie Gulbis (71) and Hee-Won Han (69) are two shots back at 7 under.
``If you're within a couple of the lead going into the weekend, that's where you want to be,'' said Gulbis, a U.S. Solheim Cup team member seeking her first tour win.
Defending champion Cristie Kerr moved to 6 under with a shot 2-under 70 and is in a six-way tie three strokes back.
``I didn't hit it well today but I still managed to shoot 2 under, which I think is a testament to how well I've been playing recently,'' said Kerr, who took the top spot on the U.S. Solheim team when she won last weekend's Wendy's Championship for Children.
Karrie Webb, a 30-time tour winner who shot 5-under 67 in the opening round, withdrew because of the death of a friend, LPGA spokeswoman Pam Warner said.
U.S. Women's Amateur champion Morgan Pressel, playing on a sponsor's exemption, survived the cut, using a second-round 70 to move to 2 under.
``There's no holding back tomorrow. It's all or nothing. I'm going birdie hunting tomorrow,'' said the 17-year-old Pressel, who also finished tied for second at the U.S. Women's Open.
Turner, who missed most of last year with a shoulder injury, said she expected to be in contention, but not in the lead going into the weekend. She prefers coming out of the pack.
``I kind of like flying under the radar, if you know what I mean,'' Turner said.
Barrett, whose only tournament win came during her rookie year in 1989, said doesn't mind being a front-runner.
``I think it's kind of nice to be in the lead, it's kind of fun,'' Barrett said. ``Why not get as much under as you can?''