Rob Wilkin, of Lenexa, Kan., held a one-shot lead over the huge field before making his lone bogey of the round on his final hole and also was at 67 with Cameron Doan of Dallas.
Tim Thelon, of Richmond, Texas, who won this tournament in 2003 and 2000, was among a group of seven players at 4 under.
Defending champion Mike Small, golf coach at the University of Illinois, was tied with six others another shot back. Small is vying to become the first repeat winner of the event since Larry Gilbert in 1981-82.
The format for the 39th National Championship was changed this year. The PGA streamlined qualifying by eliminating the Regional Championship qualifier. That doubled the size of the field -- 312 club professionals are vying for the 2006 title at Turning Stone Casino.
The tournament is being staged at Turning Stone's Atunyote and Shenendoah courses. After each competitor plays one round on each course, the field will be cut to the best 70, and ties, for the final 36 holes, which will be contested at Atunyote.
The top 20 finishers after 72 holes earn a berth in the PGA Championship in August, and the winner captures the Walter Hagen Cup, a check for $75,000 out of the $550,000 purse, and receives six exemptions to PGA Tour events.
Of the top 18 scores, 12 were carded at Shenendoah, which at 7,069 yards played 228 yards shorter than Atunyote.
Schulte, of Fishers, Ind., who quit the game for three years in the mid-1990s, rolled in a 20-foot eagle putt that barely dropped in the hole at the par-5, 603-yard No. 18 to complete his best round in seven national championships.
'I hit it reasonably close and stayed out of trouble,' said the 43-year-old Schulte, who finished seventh two years ago to qualify for the PGA, where he missed the cut. 'I'd love another shot at it.'
Schneiter, who won this event in 1995, also zoomed to the top of the leaderboard at No. 18, hitting a 3-iron from 250 yards to 15 feet of the pin and sinking the eagle putt for a 32 on the back nine.
'The second shot was just a bullet, which never left my target, the scoring tent,' said the 42-year-old Schneiter, who has won nearly $125,000 in 10 previous appearances in the tournament. 'It was a consistent day, a good solid start. This is one round, and I've got three more to go. We'll see where they fall.'
Even though he lost sole possession of the lead, the 45-year-old Wilkin was ecstatic after his sixth round in the 60s in national championship competition.
'The finish was bad, but I'm really excited,' said Wilkin, who finished in the top 10 three times and made 11 cuts in his previous 15 appearances. 'I've finished in the top 10 a couple of times, and I felt like I should have won it a couple times. so maybe three more good rounds I'll have a chance.' ^Divots: Fifty-seven-year-old Mike Harrigan, the oldest player in the tournament, shot 75, carding four bogeys and one birdie. ... Louie Bartoletti, of Wellington, Fla., had the only hole-in-one. He hit a 6-iron at the par-3, 185-yard sixth hole at Atunyote but still finished at 75.
The Golf Channel will have second-round coverage Friday at 4:00 p.m. ET