If the Leafs don't sign Marner before July 1 he'll be left exposed to restricted free agency, and another team could ink him to an offer sheet. That would be problematic for the salary-cap crunched Maple Leafs, as they would be forced to match the offer to retain Marner.
Toronto projects to enter next season with roughly $13 million in cap space, and Marner could demand an annual figure north of $10 million. Key forwards Andreas Johnsson and Kasperi Kapanen are also set to become RFAs this summer.
Marner is coming off a breakout 94-point season, which led the Leafs and ranked 11th in the NHL.