Republicans held on to a seat in the US Senate on Tuesday after a close race in the state of North Carolina, dealing another blow to Joe Biden's Democrats in their bid to take control of the chamber. Senator Thom Tillis was assured re-election after his Democratic opponent, Cal Cunningham, conceded the race. Mr Cunningham said in a statement that he had called Mr Tillis to congratulate him even though complete results from the November 3 election have not yet been announced. "The voters have spoken and I respect their decision," he said. Republicans now hold 49 seats in the 100-seat Senate compared to the Democrats' 48. All eyes are on a pair of runoff Senate elections set to take place in Georgia on January 5 likely to decide which party will control the legislative body. In the case of a tie, incoming vice president Kamala Harris would break it, according to Senate rules.