The world number one is at seven under and tied for third with Emiliano Grillo (67), with the duo sitting two shots behind Lowry.
After waiting out a delay of 3 hours, 43 minutes, Lowry played consistently enough to keep in front.
The Argentine also had three birdies after starting the round with two bogeys.
Poulter started his day with trouble after a double-bogey at the first, but he followed that up by going six under through his last 17 holes to be level with Sabbatini and overnight leader Lowry.
Three-time major victor Jordan Spieth of the United States joined a pack on 137 by completing a second-round 66 before the start of third-round play in threesomes off the first and 10th tees.
After a 311 yard drive on the 549-yard par-5 fifth, Harding chipped his third shot to 5 feet, which he rolled for one-putt birdie on the hole.
"It was hard all day", the world number one said. "Hopefully, I can roll in a few putts over the weekend".
He put his tee shot into the water on the par-3 14th for a second straight bogey.
"It was probably blowing about 30 on that putt on that green so I had to back off", Mullinax said.
"It was a flawless shot", Grillo said.
Johnson finished second at the Masters last week. "Flawless wind. It was one of those that was good, but you never expect it to go in".
Italy's Francesco Molinari, who took a two-shot lead into the final round at Augusta National before being overtaken by Tiger Woods, was unlikely to make the projected cut of even par.
The Irishman is a shot clear of Trey Mullinax, who fired a three-under 68 in his second round in SC.