Thompson's voting record has been decidedly liberal; he is arguably one of the most liberal congressmen ever to represent Mississippi. He is a founding member of the Congressional Progressive Caucus. His legislative platform focuses mainly on homeland security, civil rights, agriculture and rural issues, equal education and health care reform. In 1975, he became one of the original plaintiffs in the Ayers Case, which concerned the adequate funding of predominantly black educational institutes in Mississippi. In 2000, Thompson wrote legislation that created the National Center for Minority Health and Health Care Disparities.