A federal judge said on Wednesday that he planned to block provisions of a Florida measure that made it harder for organizations to register voters in the state. The measure, part of a broad and contentious 2011 election law in Florida, had a serious impact on third-party voter groups, like the League of Women Voters and Rock the Vote, which filed the suit along with the Florida Public Interest Research Group Education Fund. The groups asserted that the new requirements were onerous and made volunteers vulnerable to fines and even felony charges.