NHL labor talks will resume Tuesday morning in New York, with both sides still focusing on secondary matters and not the core economic issues that continue to divide owners and players in a league-imposed lockout entering its third week.

Negotiators for the league and NHL Players’ Association are expected to pick up where they left off after Sunday, when they completed three straight days of discussions. The talks focused on secondary issues, such as what should define hockey-related revenue, as well as player health and safety.

Though both sides have made progress during the latest series of discussions, they’ve failed to make much of a dent in determining how to split up more than $3 billion in league revenues between owners and players.

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No further talks are currently scheduled beyond Tuesday.

The dispute is now attracting the attention of two New Jersey senators, who are urging both sides to settle.

US Sens. Frank Lautenberg and Robert Menendez sent a letter Monday to NHL commissioner Gary Bettman and NHLPA executive director Don Fehr urging them to consider the economic impact on their state if the dispute is not resolved.

The Democrats wrote that Congress has jurisdiction over interstate commerce, which includes professional sports, and will be keeping a ‘‘close eye’’ on negotiations.

Also chiming in Monday was Wayne Gretzky, who thinks the lockout will end before the Winter Classic between the Red Wings and Maple Leafs at Michigan Stadium on Jan. 1.

‘‘I believe in my heart, maybe because I'm such a big hockey fan, that they will be playing by Jan. 1,’’ he said from Toronto during a panel discussion on personal finance.

The Hall of Fame center and former part owner of the Coyotes feels the gap between the league and its players is smaller than in 2004, when the NHL lost an entire season.

‘‘I think that in 2004 we were changing the whole landscape,’’ Gretzky said. ‘‘Ownership wanted to have some sort of revenue sharing, and once we came to the revenue sharing, the hard part — from my point of view — seems to be out of the way.

‘‘Now it’s a question of working out the number that both sides think is fair.’’

Gretzky was reluctant to analyze the labor negotiations because he’s not involved in them.

‘‘The only thing I will say is the commissioner’s office and Donald Fehr and the players’ association are very smart men; they’re both very intelligent . . . It’s a matter of sitting down and getting the deal done,’’ Gretzky said.