Karrie Webb (69) and Cristie Kerr (70) had each grabbed at least a share of the lead during the second round, but fell off the pace. They stand in a three-way tie for second place at 7-under-par 137 with Laura Diaz (68).
Jenny Rosales also shot 68 to move to 6-under-par 138. Rachel Teske is one stroke further back at minus-5 after a 3-under 69.
Sorenstam opened her round with a one-stroke lead and quickly stretched that to two shots with a 5-foot birdie putt at the first. The Swede dropped a stroke at No. 5 to fall into a three-way tie for the lead at minus-6 with Kerr and Webb.
Kerr, after a bogey at six, birdied the seventh and eighth to join Webb in the lead at minus-7. Webb got there with a birdie on No. 9.
Sorenstam moved to 7 under with a birdie at the ninth from 6 feet out, but she still trailed Webb by one after the Australian birdied the 11th.
Sorenstam, the 1997 and 2002 winner of this event, moved back atop the leaderboard as she rolled in back-to-back birdies from the 11th at Trump International Golf Club to move to minus-9.
The women's world No. 1 tripped to a bogey at the 13th, but still led by one stroke over four people. Sorenstam rolled in a 4-foot birdie putt at 15 to move her lead back to two strokes. She came right back with a 5-footer for birdie at the 16th before parring the final two holes.
'I started off really good. I hit some great shots, then just suddenly started to fall apart,' Sorenstam said. 'That second shot on nine, I had such a good tee shot, I was going for the green in two, thinking maybe I could make three. I just pretty much shanked it way up right. For me to be able to turn it around and make birdie, that was big, it was real big. I want to say that was probably the key for me to have a good back nine.'
Webb dropped from the lead with a bogey at the 12th. She managed to par her final six holes to remain at 7 under.
'I think you probably don't want to be too much more than three behind going into Sunday,' said Webb. 'It's just going to depend on the weather and the wind. I wouldn't mind seeing it at least as windy as today. Just makes you think about it.'
Kerr bogeyed the 10th to slide back to minus-6. She atoned for that error with a birdie at the 13th, but posted five pars on the final five holes to end three back.
Diaz began the day three strokes off the pace and remained there with her solid play. She opened with a chip-in birdie at the first, but faltered to a bogey on No. 5 when she was unable to get up and down for par. Diaz came right back to birdie the sixth from 9 feet out.
The 29-year-old Diaz carded consecutive birdies from the ninth to climb to 6 under. She moved to 7 under with a birdie on 13 after dropping a 6 iron within 12 feet of the cup. Then, like Kerr, she parred in.
'I started with a chip in on No. 1 and that kind of gets you a little excited right off the bat,' Diaz said. 'Then I made some putts along the way. Had a lot of chances again today, but similar to yesterday, I didn't get all of them to drop. Overall, it was a pretty good day though.'
Meg Mallon, the defending champion, fired a 6-under 66 to get back into contention. She stands alongside Lorie Kane, who tied the course record of 65, Jeong Jang, Carin Koch and Candie Kung at 4-under-par 140. Grace Park and Shi Hyun Ahn are one stroke further back at minus-3.