FORT KENT — The 18 teams that set out on a grueling, 250-mile sled dog race across the wilderness of northern Maine remained on course Sunday.

Organizers of the Can-Am Crown race said Sunday that seven teams have a substantial lead and the five lead teams are packed within half an hour of one another.

Can-Am organization president Beurmond Banville said he expects the winner will cross the finish line in Fort Kent before dawn Monday.

No one had dropped out of the race by midday Sunday.

The mushers Sunday morning came on western Maine’s boundary with Quebec and were headed for the Allagash Valley 50 miles away for a mandatory layover.

“It’s a very close race at this point,” Banville said. “There’s no clear-cut leader.”

Participants include the winner of the last two races, Ryan Anderson of Ray, Minn., along with three-time winner Don Hibbs of Millinocket, Maine, four-time winner Martin Masicotte of St. Tite, Quebec, and past winner Bruce Langmaid of Blackstock, Ontario.

The race is billed as the longest and highest-caliber race in the eastern United States. It is a qualifier for Alaska’s Iditarod Trail Sled Dog Race.

Two Massachusetts mushers won the 30-mile and 60-mile Can-Am races.

Rico Portalatin of Westhampton, Mass., won the 60-mile race with a time of 5 hours, 53 minutes. Amy deWolski of Millbury, Mass., won the 30-mile leg with a time of 2 hours, 36 minutes.