Washington, Nov 13 (IANS): Democratic Representative Kyrsten Sinema is set to win Arizona's Senate race, defeating her Republican rival Martha McSally and flipping a seat that had been in Republican hands for 24 years.

McSally conceded the hard-fought race on Monday night -- six days after the midterm elections were held on November 6 -- as county-by-county tallies of mailed-in ballots continued to increase Sinema's lead, reports CNN.

"I just called Kyrsten Sinema and congratulated her on becoming Arizona's first female senator after a hard-fought battle. I wish her all success as she represents Arizona in the Senate," McSally said in a video posted on Twitter.

The win comes despite President Donald Trump and Republicans pushing false conspiracy theories about why ballots in Arizona were taking so long to count.

Trump tweeted on November 9 that "electoral corruption" was taking place and suggested Arizona should have a new election.

The National Republican Senatorial Committee, in an email to reporters, accused the Maricopa County recorder of trying to "cook the books" for Sinema.

The upheaval comes as Arizona, long a Republican bastion, emerges as a swing state in presidential elections.

In the 2016 elections, former Secretary of State Hillary Clinton lost to Trump by just 4 percentage points there.

The result, and the state's growing Latino population, solidified Arizona as a battleground moving forward.