WATCH: A Big Litmus Test For Trump Comes Up In Georgia House Race

CHAMBLEE, GA — (CNN) The eyes of the political world are on Atlanta’s northern suburbs Tuesday as voters go to the polls in a special election that’s about much more than the House seat up for grabs.

Democrat Jon Ossoff is aiming to win the seat outright — topping 50% and avoiding a runoff. If he succeeds, it would deliver a major blow to President Donald Trump and suggest the GOP’s House majority is in jeopardy in the 2018 midterms.

The race is to replace new Health and Human Services Secretary Tom Price in Georgia’s 6th District — long a reliable Republican stronghold and the seat Newt Gingrich held on his rise to becoming House speaker in the 1990s.

It’s a “jungle primary” featuring 18 candidates — including 11 Republicans and four Democrats. If no one tops 50%, the top two finishers will advance to a June runoff.

Really, though, it’s all about Ossoff — the only candidate who is expected to be in the ballpark of 50%.

The 30-year-old former congressional staffer and documentary filmmaker carries the weight of the anti-Trump resistance on his shoulders. In large part thanks to the liberal blog Daily Kos, Ossoff raised a staggering $8.3 million in the first quarter of 2017 — a figure made possible by his stature as the only Democrat with a clear path to flipping a Republican-held seat in one of the four special elections to replace Trump Cabinet selections this spring.

Ossoff benefits from being the only serious Democrat candidate, while Republicans have seen infighting among their 11 candidates — including several with high-profile support and campaigns, including former Georgia Secretary of State Karen Handel, state Sen. Judson Hill, businessman and former state Sen. Dan Moody and Johns Creek City Councilman Bob Gray.

For Democrats, the race also offers a preview of its 2018 roadmap. The suburban district has all the characteristics — diversity, including Latino voters, higher-than-average education levels and a younger population — of those it hopes to flip in areas like Orange County, California, and the Texas suburbs.

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It took a sudden evolution for the district to become competitive at all. Mitt Romney carried it over Barack Obama in the 2012 presidential election by more than 23 percentage points, after all.

But 2016 told a much different story. Trump bested Hillary Clinton in the district by just 1.5 points. And Clinton carried Cobb County — a key population base of the district. It was the first time a Democrat had won Cobb County since Georgia’s Jimmy Carter was on the ballot.

Trump weighed in himself on the race Monday:

He followed it up by recording a robocall attacking Ossoff the evening before the special election and telling voters they need to vote for any of the Republicans in the field.

“If you don’t vote tomorrow, Ossoff will raise your taxes, destroy your health care and flood our country with illegal immigrants,” Trump said. “Vote Republican.”

The President continued with two more tweets Tuesday morning:

Republicans have long believed that all they must do is survive Tuesday without Ossoff hitting the 50% mark. If he falls short, the party believes Republican voters will coalesce around their nominee, preventing Ossoff’s numbers from climbing any higher in a runoff.

Democrats, though, note that Ossoff — who has dominated the airwaves — has still faced an onslaught of more than $4 million in attack ads from the National Republican Congressional Committee and the Congressional Leadership Fund super PAC.

“Ossoff will finally have an opponent to set up a clear and beneficial contrast. Until now, the Republican candidates have faced very little scrutiny or negative ads,” said Meredith Kelly, the Democratic Congressional Campaign Committee’s communications director.

The-CNN-Wire ™ & © 2017 Cable News Network, Inc., a Time Warner Company. All rights reserved. (PHOTO: William Walker/CNN)

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