The hill that the National Republican Congressional Committee must climb to hang onto their seats this fall just got steeper with the unexpected retirement of Congressman John Shadegg (R-Arizona).  Shadegg is currently occupying Arizona's 3rd District and his retirement will means that this state will officially be a top electoral battleground in November as half of its congressional seats are in play.

Shadegg's exit drove speculation that he was eyeing McCain's Senate seat in case the presidential candidate vacates it, but that is a remote possibility as McCain is not up for reelection until 2010, meaning he could hold onto his seat in case he doesn't win the presidency.

An open Senate seat could also potentially lead to interest from other members of the state's congressional delegation or even Napolitano, causing further open seats.

Shadegg's exit should pave the way for a crowded and expensive GOP primary in the conservative district. The winner will almost surely be greeted by a well-funded Democratic challenger, attorney Bob Lord.

Early favorites to compete for the GOP nomination include Shadegg chief of staff Sean Noble, state Treasurer Dean Martin, attorney Jordan Rose, state Sen. Jim Waring and a smattering of other state legislators.