So what happens to Delaware's at-large congressional seat if Rep. Mike Castle (R-Del.) wins a special election for Senate in November? State elections officials aren't really sure. 

Castle is running in the special election to fill Vice President Joe Biden's former Senate seat. Biden's interim replacement, Sen. Ted Kaufman (D), will serve through Election Day, with the winner of the Senate special slated to be sworn in immediately after November 2.  

"I can't find anything in the code other than a special election [to replace Castle]," said Elaine Manlove, Delaware's Commissioner of Elections.    

The complication there is that Manlove estimates it would take close to a month to pull a special congressional election together. Then the state would hold a special election to fill a little more than a month of Castle's remaining term. 

Given the added cost and logistical issues posed by such a scenario, it's an unpalatable option. Manlove said state election lawyers are poring over the code and exploring alternatives.

As The Hill's Sean Miller reported Thursday, Delaware is just one of a handful of states facing complications surrounding special election procedures. 

In June, West Virginia struggled mightily with the process to fill the late-Sen. Robert Byrd's (D) seat. And a similar dynamic is playing out in Illinois.