Scherrer fired a 6-under 66 in the third round on Saturday, waiting until almost 4 p.m. local time to tee off after a weather suspension Friday forced a re-start of the second round Saturday morning.
He stands at 21-under 195, three shots ahead of Franklin Langham and seeking his first victory of any kind since winning the 2000 Kemper Insurance Open on the PGA Tour.
Scherrer also owns two career Nationwide Tour wins -- both coming in the 1990s, when it was known as the Nike Tour.
'It's been a while since I've put three rounds together like this,' said Scherrer, whose 54-hole score was a tournament record. 'You definitely don't shoot these numbers that often. But this is what we play for.'
Langham also shot a 66 in the third round, moving into second place alone at 18-under 198. Justin Bolli had a 69 and was third at 16-under 200, while Chad Collins (68) was another shot further back at 202.
There were only 12 players within 10 shots of Scherrer's lead heading into Sunday.
Scherrer was one of the lucky players who completed their second round Friday before thunderstorms rolled into the area and dumped more than an inch of rain on Highland Springs Country Club.
Forty players had still not teed off when play was suspended for the day, leaving Scherrer with a tentative two-shot lead overnight on his 37th birthday.
He still led by two shots when the third round finally began Saturday afternoon.
On the course again, Scherrer started hot with a birdie at the first hole -- the first of four birdies on the front nine for the former U.S. Amateur runner-up. He made his only bogey at the par-4 10th, then later birdied three of four holes from the 14th to build his three-shot lead.
At the par-5 18th, Scherrer's approach hit the flag stick and nearly bounced into the water, but he was able to get up and down for par.
'That was a little unlucky. It could have gone in for three, but was certainly going to be a fairly easy putt for a birdie,' he said. 'But I was fortunate enough to get up and down, so it didn't sting too bad.'
When the second round was completed Saturday afternoon, the cut line fell at 2-under 142 with 72 players advancing to the third round.