From 1999 to 2001 Sampson served as Counsel to Senator Orrin G. Hatch (R-Utah) on the Senate Judiciary Committee. After the 2000 election, Sampson "drew on a friendship he had built in law school with Elizabeth Cheney, the daughter of the vice president, to land a job making personnel decisions in the early days of the Bush administration." Later he worked under Alberto Gonzales as Associate Counsel to the President. From there, he served as Special Assistant U.S. Attorney in the Eastern District of Virginia, and then, in 2003, became Counselor to then-Attorney General John Ashcroft. In 2005, he was promoted to be Chief of Staff and Counselor to Attorney General, Alberto Gonzales (who was sworn in as Attorney General on February 14, 2005). Sampson was "a trusted political advisor" to both Ashcroft and Gonzales.