COLUMBUS, Ohio -- Ohio Republican Josh Mandel announced Friday that he is dropping out of the race for the U.S. Senate seat currently held by Democrat Sen. Sherrod Brown.

In an email, Mandel wrote that his wife "has a health issue that will require [his] time, attention and presence."

Mandel is currently the Ohio state treasurer. He wrote that he plans to serve out the remainder of his term, which expires in January 2019.

"Understanding and dealing with this health issue is more important to me than any political campaign," Mandel wrote. "For as long as that takes, whether it is months or years, it is important that I heed my dad’s advice and be there for my wife and our kids."

Mandel was widely considered to be the front-runner to win the Republican nomination for the Senate seat in this year's election. His departure leaves Republicans Melissa Ackison, who runs a surveying business in the Columbus area, and Mike Gibbons, a banker from Cleveland.

Brown is running for re-election. He previously defeated Mandel for the seat in the 2012 election.