PORTLAND – Fan support could prove to be a major factor in the outcome of today’s 18-hole finale of the 86th Charlie’s Maine Open Golf Championship.

Amateur Shawn Warren of Windham and pro Casey Bourque, a Biddeford native, both will be in the lead group followed by family and friends as they bid for the title.

Warren fired a 6-under-par 66 Thursday at Riverside Municipal Golf Course and is tied with Todd Westfall of Clendenin, W.Va., atop the leader board at 135. Westfall posted a 69 Thursday.

Bourque also shot a 69 for 136, and Angel Franco of Asuncion, Paraguay, turned in a second straight 68 to also sit at 136.

Jerry DiPhilippo of Gorham and Rich Parker of Lebanon, N.H., are another stroke back at 137 after DiPhilippo shot a 71 and Parker a 70.

First-round leader Tom Johnson of East Greenwich, R.I., took 10 more putts Thursday than he did a day earlier and followed his opening 64 with a 74 for 138, the same as Ryan Ouellette (70) of West Palm Beach, Fla., the 2002 Maine Open champ.

“I have to do it at this tournament, with those guys out there,” said Warren of the boosters from Gorham Country Club who turn out for his rounds. “They follow me around and cheer for me.”

It appeared to work. After an opening 69 Wednesday, he was able to move up the leader board as he went deeper under par.

“Today, I started to hit a few balls close and make a few putts,” said the 19-year-old Warren.

Bourque, who plays out of Lake Winnipesaukee (N.H.) Country Club and has been competing on the Canadian PGA Tour, also is enjoying his outing.

“I love to play well around here,” said the 1995 Maine Amateur champ. “It’s cool to have some support.”

Before his round, Warren was asked about his goal for the day.

“I need to shoot 65 or 66 so I can play in the final groups,” he said.

Consecutive birdies on Nos. 4, 5 and 6 put him at 4 under for the day, then he added another birdie on 8 to turn in 31. He birdied 13 to get to 6 under for the first time but suffered a bogey on 16. He quickly regained that stroke with a birdie on 17 and parred 18 for 66 and the outright lead at the time.

“I’ll have a good time tomorrow,” he said.

Bourque made the turn at even par, but he drained a 25-foot putt on the short par-5 10th for an eagle.

“That kind of got me going,” he said. Bogeys on the next two holes wiped out the eagle, though. He finished strong by making birdies on 13, 16, and 17.

“I’ve always left here frustrated,” said the 27-year-old Bourque, playing his fourth Maine Open as a pro. “It’s a golf course that plays to my strength. I hit my wedges well, and you hit a lot of wedges out here.”

Westfall has a win on the Cleveland Golf Tour this year and played well in other events, including the Greater Bangor Open, and he’s enjoying his first trip to New England.

“The weather’s nice, the golf courses are in good shape, and the people are friendly. That’s a recipe for good golf, I suppose,” said Westfall, who made six birdies and three bogeys.