"You are clueless about what Republican voters think and feel," Greene said while attacking anti-Trump GOP lawmaker Adam Kinzinger.
Prosecutors say former GOP lawmaker Frank Artiles used a ghost campaign to "confuse voters and siphon votes" from the incumbent Democrat.
Cries of racism have done little to sway Mississippi's largely white, Republican voter base.
Republicans are losing solidly red districts, and their tax plan isn't helping.
White people almost single-handedly elected a homophobic, anti-Muslim accused child molester to the Alabama Senate.
The alleged voter suppression has disproportionately involved people of color, according to rights groups.
Polls close at 7 p.m. EDT.
The runoff for the House seat is set for June 20 in Georgia's 6th congressional district.
Gianforte was charged with misdemeanor assault after allegedly body-slamming Guardian reporter Ben Jacobs.