Haley registered her first victory in the race which has been dominated by Trump so far.

Haley, who even lost in her home state South Carolina, became the first woman to clinch a Republican primary in US history.

However, maintaining a huge lead over Haley so far, Trump is expected to contest against President Joe Biden in November's Presidential polls.

Haley will receive all 19 delegates that were up for grabs in the D.C. contest. The win gives her 43 delegates nationwide, well behind Trump's 247, CBS News reported.

Haley, a former US ambassador to the UN, won 62.9 percent of the vote, to Mr Trump's 33.2 percent, BBC reported.

Haley promises to fight every inch

In her first reaction to X after her victory, she said: "Let’s do it. Thank you, DC! We fight for every inch."

Haley campaign spokesperson Olivia Perez-Cubas said in a statement as quoted by CBS News: "It's not surprising that Republicans closest to Washington dysfunction are rejecting Donald Trump and all his chaos."