Franklin D. Roosevelt

Timing is everything in politics, and American political history might have changed dramatically if the Lieutenant Governor of New York had not suffered from diabetes.

Sen. Millard E. TydingsDuring his tenure, President George W. Bush has never endorsed a primary challenge to an incumbent member of Congress - no matter how much they disagreed with his policies.

And Bush is not alone in history. No sitting president has backed the ousting of party members (at least via popular elections) in 70 long years, since Franklin Delano Roosevelt took on Senator Millard E. Tydings and several other Democrats from across the country.