Congressional candidates don’t have to live in their district. It would help, sure, but it wouldn’t matter to a well-known candidate.

I thought this was interesting; According to Dan Bice at the Journal Sentinel: 

U.S. Rep. Reid Ribble, the freshman congressman, recently moved out of the apartment he had been renting in the 8th Congressional District and returned to the home he owns in Sherwood, several miles outside the district's boundary. But his district is being redrawn so it will include his current residence beginning in 2013.He now lives in the district represented by U.S. Rep.Tom Petri, a Fond du Lac Republican.

Sally Wood, communications director for the Committee on House Administration, said the U.S. Constitution doesn't mandate that federal lawmakers live in their districts. It simply says they must reside in the state they represent when elected, Wood said.