USA Today reports:
After roughly a quarter century in elected office, Sen. Lamar Alexander of Tennessee will retire after 2020. The former Republican governor, who has served in the Senate since first being elected in 2002, said Monday that he will not seek a fourth term in the upper chamber.
“I will not be a candidate for re-election to the United State Senate in 2020,” said Alexander. He thanked the people of Tennessee, calling them generous. His decision means for the second time in two years, Tennessee will have an open U.S. Senate race.