DeLaet, 33, from Weyburn, Sask. is tied for second with Bubba Watson who led after the first two rounds.
DeLaet's round included five birdies, one bogey and an eagle that came close to being a hole in one.
DeLaet has finished second three times in his PGA career and has twice topped $2 million in earnings in a singole season (2013, 2014). In 2013 DeLaet finished 8th in the FedEx final standings.
Harmin has rounds of 66-65-65 on the par-70 layout in Cromwell, Connecticut.