Updated 12:45p.m. ET
Sen. Rob Portman, R-Ohio, has announced he will not run for a third term in 2022 and instead will retire at the end of his term.
"This is a tough time to be in public service," Portman said in a statement Monday morning, citing hyper-partisanship in Congress.
"I don't think any Senate office has been more successful in getting things done, but honestly, it has gotten harder and harder to break through the partisan gridlock and make progress on substantive policy, and that has contributed to my decision."