The special election was held to fill the seat of former Rep. Tom Price, who was named Trump's secretary of health and human services. If he fails to do so, he will find it much harder to win against a single Republican opponent in the second election.
In a Monday, March 27, 2017 photo, Democratic Congressional candidate Jon Ossoff greets supporters outside of the East Roswell Branch Library in Roswell, Ga., on the first day of early voting.
LIASSON: We are seeing some results, but there - too few of them to draw any conclusions. If he doesn't, he'll probably have a tough time in the runoff; as Erick Erickson observes, "There hasn't been any significant poll showing Jon Ossoff equaling or exceeding Hillary Clinton's 46.8 percent" that she received in the district in 2016.
The district covers a portion of north metro Atlanta area including parts of Fulton, Cobb and DeKalb counties. "But we've got some real wind at our back at every level". But this time around, that one seat in Congress could have a serious impact.
LIASSON: It's a big deal because it's the only game in town. In a special election, that could happen, and might catch Republicans napping. It's been reliably Republican for decades. Still, Tom Price won the district by 23 percentage points.
This was a surprisingly small lead, as Mitt Romney won the district with 68 percent of the vote, and John McCain won it with 62 percent of the vote. It's suburban, highly educated.
Under normal circumstances, Ossoff wouldn't have much chance.
Under these circumstances, if Ossoff fails to get to 50, or within reasonable shouting distance, it will be remarkable. That means that he wouldn't have to face a runoff.
I call this election a ham sandwich election.
The 30-year-old former congressional aide treads carefully in this heavily Republican district.
Trump's approval ratings in national polls are among the lowest ever recorded for USA presidents for their first months in office, giving Democrats renewed hope they could capture a congressional seat with Ossoff and embarrass the new president.
Ossoff has faced criticism for the amount of money coming from outside the region and the fact that while he's originally from the district, he doesn't currently live there now.
He said Democrats were shocked into action by Trump's victory in November.
According to The Hill, The DCCC dispatched eight staffers to Georgia to build out what's become a field team of more than 70 paid staffers.
"He lives outside the district, he's a Democrat, and I just don't believe that he'd stand up to (House Minority Leader) Nancy Pelosi if the district wanted him to", West said.
Ossoff has capitalized on anti-Trump sentiments to raise more than $8 million for the race.
LIASSON: I interpret that as the White House being anxious about this race, that it's possible that Ossoff can get over 50 percent tonight. Trump retains strong support within his party, especially in the South, even as loyalists grumble about his failure to persuade a friendly Congress to pass his bill to repeal and replace Obamacare. President Trump's approval rating is low. He's made robocalls to Republicans.
The race features 18 candidates - 11 Republicans, five Democrats and two independents.