FILE - In this Nov. 23, 2019 file photo, Vice President Mike Pence and his wife Karen Pence board a military cargo jet at Al Asad Air Base, to travel to Erbil, Iraq. (AP Photo/Andrew Harnik)

Vice President Mike Pence visits the molecular testing lab at Mayo Clinic Tuesday, April 28, 2020, in Rochester, Minn., where he toured the facilities supporting COVID-19 research and treatment. Pence chose not to wear a face mask while touring the Mayo Clinic in Minnesota. It's an apparent violation of the world-renowned medical center's policy requiring them. (AP Photo/Jim Mone)

Vice President Mike Pence tours the General Motors/Ventec ventilator production facility with GM CEO and Chairman Mary Barra in Kokomo, Ind., Thursday, April 30, 2020. (AP Photo/Michael Conroy)

Vice President Mike Pence gestures while touring the General Motors/Ventec ventilator production facility in Kokomo, Ind., Thursday, April 30, 2020. (AP Photo/Michael Conroy)

Vice President Mike Pence speaks during a visit to the General Motors/Ventec ventilator production facility with Indiana Gov. Eric Holcomb in Kokomo, Ind., Thursday, April 30, 2020. (AP Photo/Michael Conroy)

Vice President Mike Pence tours the General Motors/Ventec ventilator production facility with GM CEO and Chairman Mary Barra in Kokomo, Ind., Thursday, April 30, 2020. (AP Photo/Michael Conroy)