"I can't help thinking since we just celebrated the Fourth of July and we're supposed to be a country dedicated to liberty that one of the most pervasive political movements going on outside Washington today is the disciplined, passionate, determined effort of Republican governors and legislators to keep most of you from voting next time," he told a conference of young self-styled "progressives" sponsored by the Center for American Progress, a liberal policy-research center.

Clinton condemned efforts by some Republican state legislatures to curb same-day voting registration and early voting and to institute additional ID requirements for voters at the polls.

"There has never been in my lifetime — since we got rid of the poll tax and all the other Jim Crow burdens on voting — the determined effort to limit the franchise that we see today," Clinton said.