Sen. Tim Kaine, D-Va., left, and Sen. Richard Burr, R-N.C., greet each other with an elbow bump before the Senate Committee for Health, Education, Labor, and Pensions hearing, Tuesday, May 12, 2020 on Capitol Hill in Washington. Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, is to testify before the committee. (Win McNamee/Pool via AP)

Sen. Tim Kaine, D-Va., speaks during a virtual Senate Committee for Health, Education, Labor, and Pensions hearing, Tuesday, May 12, 2020 on Capitol Hill in Washington. (Win McNamee/Pool via AP)

Sen. Tim Kaine, D-Va., speaks during a Senate Health Education Labor and Pensions Committee hearing on new coronavirus tests on Capitol Hill in Washington, Thursday, May 7, 2020. (AP Photo/Andrew Harnik, Pool)

Sen. Tim Kaine, D-Va., listens to testimony before the Senate Committee for Health, Education, Labor, and Pensions hearing, Tuesday, May 12, 2020 on Capitol Hill in Washington. (Toni L. Sandys/The Washington Post via AP, Pool)