Republican Karen Handel has won a keenly watched congressional election in Georgia and thanked President Donald Trump after avoiding an upset that would have rocked Washington ahead of mid-term elections next year.

Returns showed Ms Handel, a former Georgia secretary of state, winning about 52% of the vote over Democrat Jon Ossoff, who won nearly 48% in Georgia’s 6th Congressional District.

“A special thanks to the president of the United States of America,” she said as her supporters chanted: “Trump! Trump! Trump!”

It was Ms Handel’s most public embrace of the man whose tenuous standing in this well-educated, suburban enclave made a close race in a previously safe Republican district.

The margin allows Republicans a sigh of relief after what is being recognised as the most expensive House of Representatives race in US history, with a price tag that may exceed 50 million dollars (£40 million).

The result in a historically conservative district still offers Republicans a warning that Mr Trump, for better or worse, will dominate the looming campaign cycle.

Georgia’s outcome followed similar results in Montana, Kansas and South Carolina, where Republicans won special House races by much narrower margins than they managed in November.

Republicans immediately crowed over winning a seat that Democrats spent 30 million dollars (£23 million) trying to flip.

“Democrats from coast to coast threw everything they had at this race, and Karen would not be defeated,” House speaker Paul Ryan said in a statement.

Karen Handel
Karen Handel thanked US president Donald Trump for her victory in Georgia (Curtis Compton/Atlanta Journal-Constitution via AP)

Democrats must defend their current districts and win 24 Republican-held seats to regain a House majority next November.

Party leaders profess encouragement from the trends, but the latest losses mean they will have to rally donors and volunteers after a tough stretch of special elections.

Ms Handel, 55, will become the first Republican woman to represent Georgia in the US House, according to state party officials.

Her win comes after losing bids for governor in 2010 and the Senate in 2014, and it builds on a business and political career she built after leaving an abusive home as a teenager.

“It’s that fighting spirit, that perseverance and tenacity that I will take to Washington,” she said on Tuesday night.

She is the latest in a line of Republicans who have represented the district since 1979, beginning with Newt Gingrich, who went on to become House speaker.

Most recently, Tom Price resigned in February to join Mr Trump’s administration. The president himself struggled here, edging out Democrat Hillary Clinton but falling short of a majority among an affluent, well-educated electorate that has typically given Republican nominees better than 60% of the vote.