Patrick Caddell, a pollster for Jimmy Carter who later became a writer, consultant and co-producer on The West Wing, among other TV and film work, has died. Caddell died Saturday in Charleston, South Carolina, after suffering a stroke, Professor Kendra Stewart of the College of Charleston, told The Associated Press. He was 68. Caddell began his political career in the 1970s, working with Carter and other Democratic candidates before becoming a conservative pundit in…