On Wednesday, Sen. Ben Cardin (D-Md.) and Rep. John Conyers (D-Mich.), backed by an array of civil- and voting-rights groups, introduced a bill that would restore voting rights for federal elections to Americans with past criminal convictions upon their release from incarceration. That came on the heels of a similar but more limited bill introduced last month by Sen. Rand Paul (R-Ky.) that would apply only to non-violent offenders.