Doug Jones has become the first Democrat in 25 years to win a US Senate seat for Alabama, after a bitter campaign against Republican Roy Moore.
His unexpected victory deals a blow to President Donald Trump, who backed Mr Moore, and narrows the Republican majority in the Senate to 51-49.
Mr Moore has so far refused to concede, saying “it’s not over”.
He fought a controversial campaign, in which allegations surfaced of sexual misconduct with teenage girls.
Mr Moore, a firebrand conservative who has said he believes that homosexual activity should be illegal, has repeatedly denied the claims against him.