Ohio State Treasurer Josh Mandel (R) is giving up his offer in the Senate, citing his wife's health problems.
"I am finishing my campaign for the US Senate to be there for my wife and our three children, it was a difficult decision for us, but it is the right one," Mandel wrote.
"Understanding and dealing with this health problem is more important to me than any political campaign."
Mandel went on to say that he will fulfill his tenure as treasurer, which ends in 2018.
The Ohio Republican had been the main candidate in the race to face Brown: he was the party's candidate in the Senate race. 2012 against Brown, losing around 6 points that year.
Even so, Mandel narrowly led Brown in a May survey published by Gravis Marketing. By contrast, Brown led Mandel by 19 percent in a June Luntz Global survey.
Mandel's departure leaves Gibbons as the main candidate in the race. Gibbons had been developing a series of local endorsements of his own while trying to frame himself as the foreign option for the primary voters of the Republican Party.
Gibbons had $ 640,000 in the bank until September, after lending his campaign around $ 570,000. The fundraising report for your campaign through the end of 2017 will take place at the end of January.