The complaint had accused the Sanders campaign of accepting excessive contributions.
Voters enrolled in a small right-wing party thinking they were registering as independents.
Mississippi's "religious freedom" law, a look at Jerry Brown's career, how Ted Cruz could become president and more in this week's top political stories.
Clinton maintains the lead in polls but the gap has narrowed ahead of the April 19 primary.
March marks the second month in the presidential election’s primary season.