The Tampa Bay Lightning and longtime star center Steven Stamkos are unlikely to reach an agreement on a new deal prior to the start of NHL free agency.

Stamkos, the team captain since March 2014, will become an unrestricted free agent Monday at noon ET if the two sides remain without a deal.

"If we had reached an agreement at this point, we would gladly have sent out a press release announcing that agreement," Lightning general manager Julien BriseBois said. "So as we stand here right now, we haven't been able to reach an agreement yet. I don't know if we will be able to reach an agreement.

"But we met with Steven's agents again yesterday. Both sides are still interested in getting a deal done, but we haven't been able to agree to terms that are satisfactory for both sides."

Stamkos' agent, Don Meehan, doesn't sound optimistic a deal will be reached before the deadline. "He will be a free agent on July 1," Meehan told Sportsnet.

The two sides were unable to reach a deal before the 2023-24 season, which disappointed Stamkos, he said.

Stamkos, 34, was the No. 1 overall selection of the 2008 NHL draft and has spent 16 seasons with the Lightning.

He is the club's all-time leader with 555 goals, 1,137 points and 1,082 games. He has won two Stanley Cups (2020, 2021) with the franchise and has 50 goals and 51 assists in 128 playoff games.

This past season, Stamkos had 40 goals and 41 assists in 79 games. It marked the seventh time he has scored 40 or more goals. A seven-time All-Star, Stamkos also authored his first career four-goal game last December.

But now there is a strong chance Stamkos could depart.

"At this point, it's premature to start answering those types of questions," BriseBois said. "If we get to that point, we'll address it at that time."

Stamkos came close to becoming a free agent in 2016 before signing an eight-year, $68 million deal just before the start of free agency.

Coming off that deal that carried an $8.5 million salary cap hit, Stamkos will easily be one of the biggest headliners next week. Though they lost in Round 1 to the state rival Florida Panthers in May, the Lightning, in a five-game series, saw the best of Stamkos, who finished with five goals and six points.

The Lightning also are hopeful of working out a contract extension with defenseman Victor Hedman, who has one season left on an eight-year, $63 million contract. Hedman, 33, had 13 goals and 76 points in 78 games this season, his 15th with the club.

"We've had discussions with Victor's agents about an extension," BriseBois said. "In his case, we have more runway before we have to get a deal done, as he still has one year left on his current agreement. That being said, the plan remains to be in a position to announce an agreement on a new contract for Victor in the coming days."

Information from Field Level Media was used in this report.