Sen. Chuck Grassley of Iowa tweets he has tested positive for COVID-19. At 87, he is the oldest Republican serving in the Senate. Grassley chairs the Senate Finance Committee and is the president pro tempore of the Senate, making him third in line for the presidency after the vice president and speaker of the House. He is the sixth senator to test positive for COVID-19. In a tweet, Grassley said he is "Feeling good." Ref. USAToday.