A Republican, Mandel was trying to win the seat currently held by Democrat Sherrod Brown, who is seeking his third term.
His decision, announced today, involves an unspecified health issue involving his wife.
“I am writing today to let you know that I am ending my campaign for U.S. Senate in order to be there for my wife and our three children,” Mandel said in a post on Twitter.
The Ohio Republican Party confirmed Mandel’s decision.
"Josh Mandel has made an honorable decision to be with his family in a time of need,” Ohio Republican Party Chairman Jane Timken said. “While we are saddened to see him leave the race, we understand, and offer our thoughts and prayers to his family.”
"Our focus is, and will continue to be, on electing Republicans statewide and continuing to make Ohio stronger," Timken added.
In 2012, Mandel lost to Brown by 6 percentage points.
“I will continue to serve out the remainder of my term as state treasurer and hope to have the opportunity to serve my state and country again in the future,” Mandel told the Columbus Dispatch in an email. “But in the meantime, I must put my family first. I’m grateful for your understanding.”
Melissa Ackison, Donald Elijah Eckart and Mike Gibbons remain in the Republican race involving the Senate seat. The filing deadline is Feb. 7.
In a statement, a Brown campaign spokesman told the Columbus Dispatch: “At this time, we wish Josh, Ilana and their family the best of health. We hope for Ilana’s full and speedy recovery.”