Cook County Commissioner Sean Morrison (R-17th) announced Thursday he will not run for reelection next year, saying he believes "public service should be a season of contribution, not a lifetime occupation, and it is important that I lead by example."

Morrison, the lone Republican on the 17-member Cook County Board, also said the Democratic party's supermajority was a factor in his decision not to seek another term in office, saying his fellow commissioners' "ideological priorities diverge sharply from my own deeply held personal, ethical, and spiritual convictions."

"I respect that many of my colleagues are good-hearted individuals who genuinely believe in their approach to governing, but those approaches often stand in conflict with the principles that brought me into public service. While I have worked vigorously to bring balance, transparency, and accountability, I also recognize the limits of what one voice can realistically achieve in a system so overwhelmingly weighted to one side," Morrison said in a statement.

Morrison was first appointed to his seat on the Cook County Board in July 2015, to complete the expiring term of Elizabeth Ann Doody Gorman, who had resigned to take a job in the private sector. He was elected to his first full term in 2018, and reelected in 2022.

In April 2016, Morrison was elected as chairman of the Cook County Republican Party. He resigned from this seat this past April, and was replaced by the previous chairman, Aaron Del Mar, who is now running for lieutenant governor as GOP candidate for governor Darren Bailey's running mate.

The entire Cook County Board, including its president, Toni Preckwinkle, are up for reelection next year. Morrison has been the only Republican on the board since 2022, when longtime Commissioner Peter Silvestri retired at the end of his seventh term in office.