Regent Mary Andringa has resigned from the state Board of Regents.

The Republican and board chairwoman of Vermeer Corp. snagged the seat in a term starting May 1, 2015.

Her resignation is effective Saturday.

Gov. Terry Branstad has the power to appoint a new regent to the seat, with Senate confirmation. The seat’s term ends in 2021.

“I underestimated the time required to fully serve in this role given my pre-existing commitments and responsibilities,” Andringa said in a statement. “I have come to realize that I do not have the capacity necessary to fulfill the needs of this position at a level that is acceptable to me.”

Andringa said she was proud of serving as a regent and proud of the regents’ accomplishments.

In response, Iowans Defending Our Universities, an advocacy group formed after the appointment of Bruce Harreld as University of Iowa president, called on Branstad to appoint a Democrat to the board in an email to supporters.

Iowa law states the regents should not consist of more than five members of the same political party.

The organization also called for Branstad to appoint a regent with “an understanding of higher education and a willingness to advocate for state funding,” as well as pointing to the state Senate to refuse to confirm any appointee who does not “meet the letter or spirit of the law’s emphasis on a diverse Board of Regents.”