Bill Lunde is one stroke behind Stadler at 10-under-par 204 after a third-round 68. Matt Peterson, Sonny Skinner and Gavin Coles share third place at 7-under-par 209.
Stadler, who lead after round one, dropped in back-to-back birdies from the second to move to minus-10. He tripped to a bogey at the seventh at Peek 'n Peak Resort's Upper Course, but capped his opening nine with a birdie at the ninth.
'The wind was howling,' Stadler said. 'The trees are so tall and you're down below it, it was cloudy and that's the only way I could tell which way the wind was going. I think Chicago takes all the glamour from Denver, but it blows there, too. I grew up playing in windy conditions like this and don't really mind it. It puts a premium on ball-striking.'
Stadler, son of Champions Tour player Craig Stadler, faltered to another bogey at the 13th to slip back to minus-9. He fought back with a birdie at the very next hole and birdied the last to secure the lead after round three.
'A win would be huge,' said Stadler, who is playing this week on a sponsor exemption. 'I'd get out here and wouldn't have to try to Monday qualify my way in. It'll be too soon to think about it until the flagstick goes in the hole tomorrow.'
Lunde, who describes himself as a veteran rookie, birdied three of his first seven holes to get to minus-9. He stumbled to a bogey at the par-3 10th.
The 28-year-old came right back to birdie No. 11 to get back to 9 under. He reeled off five straight pars from the 12th before birdieing the 17th to get within one shot of Stadler.
'I learned a lot from New Zealand,' said Lunde, who shared the lead before tying for second at the New Zealand PGA Championship. 'When it's windy, anything around par is going to be a good score. You try to be patient because if you hit a couple of bad shots it's easy to get mad and throw a couple more away.'
Jeff Quinney, who shared the overnight lead with Anthony Painter, stumbled to a 3-over 75. He shares sixth place at 6-under-par 210 with Victor Schwamkrug, Craig Lile, Jaxon Brigman and Jason Buha. Phil Tataurangi and Bubba Watson are one stroke further back at minus-5.
Painter, meanwhile, posted the worst round of the day at 10-over 82. He carded two birdies and four bogeys on the front side, before one bogey and three double bogeys on the back nine. He plummeted from a tie for the lead into a share of 61st place entering the final round.