It was a quick turnaround for Rivera.
On Wednesday, he posted on Twitter he was, “Pondering running.” A day later, he said he would not seek public office.
Portman, a Republican from Ohio, announced in January he would not run for reelection. He’s held the office since 2011.
Two high-profile Republicans, Ohio Lt. Gov. Jon Husted and Rep. Jim Jordan, have also announced they will not run. Former state treasurer Josh Mandel entered the race.
On the Democratic side, Rep. Tim Ryan of Ohio’s 13th Congressional District and former director of the Ohio Department of Health Dr. Amy Acton have expressed interest in the open seat.