A letter submitted to the U.S. Senate that states it was sent by physicians in support of Robert F. Kennedy Jr.’s nomination as secretary of Health and Human Services includes the names of doctors who have had their licenses revoked, suspended or faced other discipline, The Associated Press has found. The letter was meant to lend credibility to Kennedy’s nomination, which has faced strenuous opposition from medical experts due to his two decades of anti-vaccine activism. Republican Sen. Bill Cassidy of Louisiana, a medical doctor who boasts on his official website of an effort he created to vaccinate 36,000 children against hepatitis B, expressed hesitancy about Kennedy's nomination and is seen as a key vote.