By Andy Sullivan
SANDY SPRINGS, Ga. (Reuters) - U.S. Democrats hope frustration with President Donald Trump will give them a surprise victory on Tuesday in an election to fill a vacant congressional seat in suburban Atlanta that has been held by Republicans for decades.
As voting concluded on Tuesday, Democrat Jon Ossoff, a 30-year-old political novice, was expected to come out atop a field of 18 candidates vying for a U.S. House of Representatives seat that was vacated when Trump named Tom Price as his health secretary.
The drama hinged on whether the documentary filmmaker would win an outright majority of the vote, which would send him to Congress, or if he would fall short of 50 percent and be forced into a June 20 runoff with one of the 11 Republicans in the race.
An Ossoff win would not tip the balance of power in Washington but could weaken the already shaky hold Trump has on his fellow Republicans by encouraging lawmakers to distance themselves from him.
"It's a test case for how far a Democratic candidate can go in a Republican district on the strength of opposition to Trump," said Todd Rehm, a Georgia Republican strategist who is not affiliated with any candidate in the race.
The district, which encompasses a swath of well-heeled suburbs north of Atlanta, has elected Republicans to the House since the late 1970s, but Trump carried it by only 1 percentage point in the November presidential election.
Republicans in the race are split among Trump supporters and candidates trying to hold the president at arm's length. Party officials say they can beat Ossoff once the primary is over and they unite behind a single candidate.
The party avoided embarrassment last week when it narrowly held a conservative Kansas seat vacated when Trump tapped Republican Representative Mike Pompeo to head the Central Intelligence Agency.
'MAKE TRUMP FURIOUS'
With the slogan "Make Trump Furious," Ossoff aims to galvanize opposition to a president struggling with an approval rating that has not topped 50 percent since he took office on Jan. 20, according to Reuters/Ipsos polling.
Ossoff has drawn volunteers and donors from out of state who see the race as a way to strike a blow against Trump. He raised a stunning $8.3 million in the first three months of the year, fueling a robust campaign.
"They were ringing my phone off the hook," said Kim Fambro, 45, who said the outreach convinced her to vote for Ossoff.
Trump blasted Ossoff on Twitter and said in a robocall that the Democrat would "raise your taxes, destroy your healthcare, and flood our country with illegal immigrants."
Ossoff said on CNN that Trump was misinformed about his positions and that he was focused on issues affecting the region, not Washington.
Republicans have responded with millions of dollars of spending of their own, casting Ossoff as an inexperienced outsider who does not live in the area he hopes to represent. Ossoff, who grew up in the district, says he will move back if he wins.
(Reporting by Andy Sullivan; Additional reporting by Susan Heavey in Washington; Editing by Peter Cooney)