Paul Kane explains why the succession plan for deceased Sen. Robert Byrd is unclear, and lends itself to legal challenge:

A quirk in West Virginia’s laws appears to state that the replacement will likely hold the seat for the remainder of the late senator’s record ninth term, through 2012; therefore, Byrd’s death would not impact the partisan makeup of the chamber, nor would it directly impact the pending 2010 elections. However, there is some ambiguity in the law that has left some election experts questioning the what should happen with the seat.

State law mandates that, if a Senate vacancy occurs more than 2 1/2 years before the term is up, a special election be held to fill the seat. There were exactly two years, six months and five days left in Byrd’s term when he died.

However, the law states that the special election would only occur after a candidate “has been nominated at the primary election next following such timely filing and has thereafter been elected.”

Because West Virginia held its 2010 primary almost two months ago, many election law experts read that provision to mean that the “next” primary would not be until spring 2012, before the general election in November, 2012. Some legal experts, speaking privately out of deference to Byrd’s family, wondered whether this wording could open a legal challenge and force a special election this November, similar to those happening in Delaware and New York to fill the remainder of Senate terms vacated by Vice President Biden and Secretary of State Hillary Rodham Clinton.