PORTLAND — Former U.S. Sen. George Mitchell will be the keynote speaker at the May commencement ceremony for the University of Southern Maine, the university announced Tuesday.

“USM is honored to have one of our country’s most respected statesmen speak at our 2016 commencement,” USM President Glenn Cummings said in a news release.

“George Mitchell’s extraordinary service as a U.S. senator and a diplomat has always made Mainers proud. And his work to help young Mainers achieve a college education has created an unmatched legacy,” Cummings said.

A native of Waterville, Mitchell served as a U.S. attorney and federal judge before accepting a 1980 appointment to succeed Edmund Muskie in the U.S. Senate. He served from 1980 until 1995.

He spent his final six years in the Senate as majority leader, shepherding a variety of bills from child care and clean air, to low-income housing and the landmark passage of the Americans with Disabilities Act.

After leaving the Senate he became a sought-after diplomat.

In 1995 he served as a special adviser to President Bill Clinton on Ireland. From 1996-2000 he served as the Independent Chairman of the Northern Ireland Peace Talks helping to broker the Good Friday Agreement, an historic accord ending decades of conflict agreed to by Ireland, the United Kingdom and the political parties of Northern Ireland.

In 2006 and 2007, he led the investigation into the use of performance-enhancing drugs in Major League Baseball.

In 2009, he returned to international relations and served for two years as U.S. special envoy for Middle East Peace.

Meanwhile, he maintains his ties to home.

In 1995, he created the Mitchell Scholarship Program to help Maine students pay for college. Four years later, the program became part of the Mitchell Institute.

USM’s graduation will be held at 9 a.m. May 14 at the Cross Insurance Arena in Portland. The ceremony includes graduates of the three campuses in Gorham, Portland and the Lewiston-Auburn College.