From the New Haven Independent:
A day after U.S. Sen. Joe Lieberman declared himself a "devoted Democrat" on national TV, peace activists in his hometown of New Haven asked the local registrar of voters (Sharon Ferrucci, pictured) Monday afternoon to strip him of his party affiliation because of his third-party reelection bid against party-endorsed Ned Lamont....
The activists cited Section 9-61 of Chapter 143 of the state statutes in their request. That section allows for a Democrat's party afffiliation to be "stricken or excluded" for two years if he runs for office as a candidate of a different party. To read the section of the statute, follow these steps: Click here. Then type "9-61" in the box for "Section number." Click on "Chapter 143." Finally, click on "Sec. 9-61."
UPDATE: As lalolola notes in the comments:
Joe is not an 'Independent', Joe is the candidate of the Connecticut for Lieberman (CT4L) party. The Independent Party is a registered entity in Connecticut that has no association with Holy Joe.