Those four voters could have been enough to change the outcome of the election.
Erwin appeared to win the December election by two votes, but now he'll have to face Gasaway again in an April 9 election.
It will be the third Republican primary election between the two candidates. There are no Democrats in the race, meaning the primary will decide who wins.
“Leaving the constituents of the 28th District unrepresented during this crucial period is truly a travesty,” Erwin said. “Our community to have no voice or vote on important legislation to fund government operations, fix rural hospitals, improve education and protect our Constitutional rights.”
Sweat also invalidated last May's first primary election because Habersham County election officials incorrectly assigned dozens of voters to the wrong state House district. Erwin had a 67-vote lead in that election.
Under Georgia law, elected offices become vacant when a judge orders a new election.
A spokesman for House Speaker David Ralston, a Republican from Blue Ridge, said he won't take action on the House District 28 seat until the judge's order is received and reviewed.
Georgia Secretary of State Brad Raffensperger opened a voter fraud investigation Thursday into allegations that several people illegally voted in the House District 28 race.