Is one of the U.S. Senate’s top Republican squishes on his way out in 2020? Rumor is, Senator Lamar Alexander, R-Tenn. is considering retirement. The 76-year-old moderate has served as governor of Tennessee, secretary of education under President George H.W. Bush, and was elected to the U.S. Senate in 2002. He has run for president twice. Were Alexander to run for and win reelection in 2020, he would be 86 at the end of his term. But should he choose not to, former NFL quarterback Peyton Manning has been mentioned as a potential candidate.