Gov. Mark Dayton added his political heft Tuesday to a group of state senators demanding more information about why Shannon Miller is losing her job as head coach of the University of Minnesota Duluth women's hockey team.

Thirteen DFL state senators sent the letter to University of Minnesota President Eric Kaler and Duluth Chancellor Lendley Black, hinting at sexism in the school's recent decision to release Miller after this season, even though she had led the UMD Bulldogs to five national championships. "Governor Dayton has requested to add his name to the letter as a signatory," his spokesman, Matt Swenson, said Tuesday.

"It is our understanding that [UMD] is citing financial reasons for letting Ms. Miller go," the letter read. "However, the coach of the men's hockey team [Scott Sandelin], who earns a salary that is $20,000 per year higher than Ms. Miller's and has a lower winning percentage, is being retained."

The letter was sent by Sen. Katie Sieben, of Newport, and cosigned by a dozen other DFL senators, most of them men. All but two are from the Twin Cities. None represent the Duluth area.

Responding in a letter Tuesday afternoon, Black called the university's decision "a very difficult one." He described it as a financial decision, but one with other factors, and said it came after a comprehensive analysis.

"In this case, these included what is best for student-athletes, program performance during the past four-and-a-half seasons, and the overall direction of the program — including finances and the fact that Coach Miller is the highest paid women's hockey coach in the nation," Black wrote. Later in the letter Black praised Miller's performance, but added, "recently the team has not achieved competitive success at the same level."

The Bulldogs women's team is 19-10-5 this season, and in the hunt for a berth in the national playoffs as the regular season winds down and conference playoffs follow. The Bulldogs have not made the eight-team national tournament since 2011.

Miller's pending departure sparked a national debate about the treatment of female coaches and athletes. In December, Black, along with UMD athletic director Josh Berlo, told Miller that her contract would not be renewed in June, despite her past national titles and a record of winning more than 70 percent of games in 16 seasons. Miller herself said the decision violated Title IX, the federal law prohibiting gender-based discrimination at schools that get federal funds, and she has hired an attorney.

With $215,000 in total compensation this season, Miller is indeed the highest paid women's hockey coach in the U.S. And, as Black noted in his letter back to lawmakers, her team has recently struggled against conference rivals, going 3-26-7 vs. Minnesota, Wisconsin and North Dakota over the past three seasons.

The inquiry from senators is more than symbolic: The Legislature determines a good deal of the University of Minnesota's funding. This year, Kaler is seeking an additional $127 million from lawmakers on top of $1.2 billion in state dollars the system got in the previous two-year state budget. In his own budget proposal, Dayton sought about three-quarters less than that. Given that, Senate DFLers stood to be the system's best ally at the Capitol for a bigger funding boost, with Republicans in charge in the House.

Sieben is the DFL's assistant majority leader. A spokeswoman for the senator said Tuesday night that Sieben had nothing further to add for now.