He has worked for Democratic presidential candidates George McGovern in 1972, Jimmy Carter in 1976 and 1980, Gary Hart in 1984, Joe Biden in 1988, and Jerry Brown in 1992. He also worked for Colorado Senate candidate Andrew Romanoff in 2010.
He has served as a consultant to various movies and television shows, most notably the movies Running Mates, Air Force One, Outbreak, In the Line of Fire, and the serial drama The West Wing. He was also a marketing consultant on Coca-Cola's disastrous New Coke campaign.
In 1988, Caddell left the Democratic Party after an acrimonious lawsuit with a Democratic consulting firm, Caddell, Doak and Shrum. Republicans would often cite Caddell's tirades against the Democratic Party when they spoke on the floor of the House and the Senate.
According to researchers, Caddell had wide influence in the Carter White House, and was the chief advocate of what later became known as Carter's "malaise speech".