Massachusetts Gov. Patrick picks ex-aide as interim senator

Massachusetts Gov. Deval Patrick has selected his former chief-of-staff William "Mo" Cowan to serve as interim U.S. senator until a special election to fill the seat left vacant by Secretary of State designate John Kerry.

A person with knowledge of the appointment who spoke on condition of anonymity because an official announcement has not been made says Patrick picked Cowan. He will serve until the June 25 special election.

The Democratic governor gave little indication whom he favored during his deliberations. The only possible candidate he confirmed speaking with was former Congressman Barney Frank, and then only after Frank told reporters he'd spoken with Patrick.

Michael Dukakis, the former governor and 1988 Democratic presidential nominee, and Victoria Kennedy, widow of U.S. Sen. Edward Kennedy, had also been mentioned as possible candidates for the interim post.