Democrat Raphael Warnock won re-election to the US Senate in a hard-fought Georgia runoff on Tuesday, strengthening his party's razor-thin majority.

Warnock's projected victory was narrow. With 99% of the estimated vote counted, he led Walker by 50.8% to 49.2%, according to Edison Research.

Democrats now are on track for a 51-seat majority in the 100-seat Senate.

Walker's defeat is also a setback for Donald Trump who has announced to run for president in 2024. Trump endorsed Walker and dozens of other high-profile Republicans in this year's midterm elections, but he ends with a mixed record in his most competitive contests.