Beau Biden

Beau Biden passed up the opportunity fill that very Senate seat in 2008 when his dad ascended to the White House.

The younger Biden chose instead to remain Delaware's attorney general; a job he's had since 2007

Source: http://whitehouse.blogs.foxnews.com/2010/05/11/vice-president-bidens-son-hospitalized-father-and-son-in-familiar-situation/