Democrat Jon Ossoff and Republican Karen Handel are facing off Tuesday in what has become the most expensive House race in history.
The candidates, their parties and super PACs have poured more than $50 million combined into the effort to win a single House seat in the northern Atlanta suburbs.
More than 140,000 voters cast their ballots early -- an astounding number for a special election, and one that nearly matches presidential contests.
The race is being viewed nationally as a gauge of whether President Donald Trump's sagging approval ratings are a drag on Republicans that could threaten the party's control of the House in the 2018 midterm elections.
Democrats, meanwhile, see in Georgia an early test of their strategy of trying to win typically Republican seats in suburban areas -- districts that are relatively highly educated, wealthy and diverse.
President Donald Trump weighed in on Twitter late Monday and early Tuesday, attacking Ossoff for living just outside the district, claiming Ossoff will raise taxes and calling Handel a hard worker "who will never give up!"
Ossoff and Handel were the top two finishers in an April 19 primary, advancing to the one-on-one runoff election.
The district has historically leaned heavily Republican. Former Rep. Tom Price, whose departure to become Trump's health and human services secretary led to the special election, won each time he was on the ballot since 2004 with more than 60% of the vote. Mitt Romney carried the district by more than 23 points when he faced former President Barack Obama in 2012.