Following up on this post, you can read the Corrine Brown and Mario Diaz-Balart lawsuit at this link. In addition to raising a somewhat unusual claim under section 5 of the VRA, the complaint also alleges a violation of the U.S. Constitution, Article I, Section 4, which vests in each state legislature the power to choose the rules for selecting members of Congress (subject to congressional override). I don’t think that argument is likely to succeed, for reasons I’ve explained in this article on a related topic: the ability to use the ballot measure process for changing the rules for choosing presidential electors.