The Weyburn, Sask., native tied for a low round of the day with a 65 and was helped out when Bubba Watson made three bogeys on his last six holes.
DeLaet, Watson and Charley Hoffman are all at 10-under par heading into Sunday's final round at the TPC of River Highlands. Watson shot an even-par 70.
DeLaet is playing this week in New England but many of his thoughts remain north of the border. The heavy rain and flooding in Alberta forced the PGA Tour Canada to cancel its event this week.
DeLaet, the 2009 Canadian Tour player of the year, has pledged to donate $1,000 for every birdie he makes this weekend and $2,500 for every eagle to help the relief effort.
"It's a pretty small part, what we're doing, but anything helps," DeLaet said. "There's a lot of help from everyone all across Canada."
DeLaet first made it to 10-under after beginning his back nine with four straight birdies. A bogey at the difficult par-3 16th put a slight damper on his round, but DeLaet finished strong by delicately rolling in a downhill putt from the fringe on the 18th hole to get into the clubhouse at 10-under.
"I did play well pretty much all day. I had a lot of good birdie chances on the front nine, just couldn't really seem to find the hole," DeLaet said. "Julien (Trudeau), my caddie, just told me to stay patient."
Brad Fritsch of Ottawa hit 70 to finish the round nine shots back of the lead.
Justin Rose, less than a week after his U.S. Open victory, sits at 7-under par and in a tie for seventh place after a second straight 68.
Watson made three birdies in his first six holes Saturday and was ahead by four shots after the third. But bogeys on Nos. 13, 15 and 17 brought the 2011 Masters champion back to the field.
Watson, who won the 2010 Travelers, is trying to become the seventh man to win the event at least twice. Arnold Palmer and Phil Mickelson have also done it.
Watson began the day with a two-shot lead and immediately began to extend it. After saving par on the first hole with a sliding, 7-foot putt, Watson made birdie at No. 2 by hitting a wedge some 2 feet from the hole. He followed that by draining a 30-foot putt from the front edge on No. 3 for a second straight birdie.
Another birdie at the par-5 sixth gave Watson a four-shot lead and he seemed ready to lap the field. Watson also made relatively lengthy par-saving putts on Nos. 7 and 10.
The smallest cracks in Watson's armour appeared at the par-5 13th, where his drive faded too far left and ended up in a fairway bunker.
He was still short of the green after three shots and eventually made bogey, his first of the day and first in his last 30 holes.
He made another bogey at the easiest hole at the TPC of River Highlands, the 296-yard, par-4 15th. His drive left him just 50 feet from the hole but his putt through the fringe didn't make it up the steep hill in front of the green. A chip and two putts followed, moving Watson back to 11 under.
Watson's final bogey came on the 17th and was the result of a tee shot pushed left into a fairway bunker.
The lack of rain recently combined with an increase in the wind late Saturday made TPC of River Highlands, one of the shortest courses on tour, increasingly difficult for the players.
"I think we've never seen the golf course like this, as firm as it is and as firm as some of the greens are," Watson said. "It's hard to get to certain points, so a lot of people probably played it safe."
After shooting a 61 in the opening round, Hoffman struggled and shot 73 on Friday. But he bounced back with a 66 Saturday in a round that included five birdies.
Hoffman, who has won twice previously on the PGA Tour, was leading the Travelers last year when he hit his tee shot on the par-4 17th into the water. He finished in a tie for second.
He said he doesn't expect a similar result this year.
"Obviously, if I get on 17 tee, I'd be lying to say I'm not going to think about that tee shot," Hoffman said. "But I'm a much more mature, better player than I was a year ago and don't feel uncomfortable on that tee shot."