ATLANTA — Reports that tens of thousands of Georgia voters, predominantly African-Americans, were placed on a list for further scrutiny have exploded into the Georgia governor’s race, leading to bitter exchanges between the candidates and leaving many residents uncertain what to expect as the state began early voting Monday.

The uproar over voting seems almost an inevitable development in the race, which pits two candidates on opposite sides of the nation’s voting wars who have battled with one another over access to the polls for years.

Stacey Abrams, the Democrat, who is hoping to be the nation’s first black female governor, forged her political profile through a group she founded that in the last five years has registered thousands of new minority voters. Her opponent Brian Kemp, Georgia’s secretary of state since 2010, has advanced strict voting rules that he says are needed to combat fraud, but which critics call a form of voter suppression directed at precisely the new voters Ms. Abrams is aiming to bring to the polls.

Their race is the latest example of how contentious and far-reaching voting issues have become in American politics, where once largely nonpartisan issues have been weaponized to gain an edge.