Michigan State football coach Mark Dantonio is retiring after 13 seasons.

He made the announcement Tuesday on Twitter and was scheduled to speak at a news conference at 6:30 p.m.

Dantonio's decision to retire was made last week, according to multiple persons with knowledge of the situation. The sources spoke on condition of anonymity because they were not authorized to speak on the decision.

Dantonio, the all-time winningest coach in MSU history, finishes his career with 114 wins for the Spartans along with three Big Ten championships, a Rose Bowl win and a berth in the 2015 College Football Playoff.

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“Today marks one of the most difficult decisions that I have ever made here at Michigan State,” Dantonio said in his statement released on social media. “I would first like to thank our fans, alumni, and our administration; both past and present staff and especially our current and past players and coaches for all their support, hard work and dedication over these past 13 years. You have truly helped make my dreams come true.

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“Every February since 2007, I have reset this program in preparation for the next year’s challenges. After much reflection and discussion with my family, I feel that it is now time for change as we enter into a new decade of Michigan State Football."

The front-runner to replace Dantonio is Cincinnati head coach Luke Fickell, according to sources with knowledge of the athletic department’s thinking. No deal is in place, the sources said.

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Defensive coordinator Mike Tressel has been named the team's acting coach as the school searches for a permanent replacement.

In the statement posted on social media, Dantonio said his plan is to stay within the MSU athletic department "in a role involving special projects, especially transitioning our players, both current and incoming, to their next challenges."

More:How Dantonio retired late enough to get $4.3 million bonus

On Jan. 16, Dantonio was owed a $4.3 million bonus "in recognition of his long-service to the University." That payment is due on or before March 31, according to the terms of the agreement that were added on Feb. 19, 2016, after MSU's College Football Playoff season.

“Mark Dantonio has provided outstanding leadership for the Spartan football program for the last 13 years,” MSU athletic director Bill Beekman said in a statement released by the university. “As the all-time winningest coach in school history, he’s raised the bar for Michigan State football. He’s mentored young men and led them to success on the field, in the classroom and in life, while serving as a great ambassador for Michigan State University. As we begin the search for Mark’s successor, we will look for the right fit who will continue the success at both the conference and national level.”