McSally called Sinema to concede the race. McSally unsuccessfully tried to paint her as a liberal Democrat.
For now, the win in Arizona means that Democrats have narrowed GOP gains in the Senate to only one seat so far - Republicans defeated incumbents in North Dakota, Indiana and Missouri, but Democrats flipped seats in Nevada and now Arizona. Sinema started as an overt liberal but developed a reputation for compromise among her Republican peers, laying the groundwork to tack to the center. In 2003, Sinema said she didn't care if Americans travel to Afghanistan to join the Taliban.
Kyrsten Sinema's campaign has said that her lead in the Senate race is "insurmountable". "I wish her all success as she represents Arizona in the Senate", McSally said in a video posted on Twitter Monday night.
In other races: Democrat Katie Hobbs, who had taken a 150-lead over Republican Steve Gaynor after Maricopa County reported its tally today, has fallen behind Republican Steve Gaynor by 259 votes in the race for Arizona Secretary of State.
Sinema, a member of the centrist Blue Dog caucus in the House, had campaigned as a moderate. Jeff Flake, a critic of the President's incendiary rhetoric.
Kyrsten Sinema delivered an acceptance speech citing the inspiration of late Senator John McCain as an example of what Arizonans looked for in a senator.
The upheaval comes as Arizona, long a Republican bastion, emerges as a swing state in presidential elections. "She wanted McSally to pay for Trump", Lah explained.
Sinema attacked McSally's leadership of last year's failed Affordable Care Act repeal effort as a sign that she would not protect Arizona residents with preexisting medical conditions. That forced her to move to the right, especially on immigration.
Sinema, 42, has a law degree, worked as a social worker and was a political activist in her 20s, running as an independent Green Party candidate for the Arizona House. President Trump won Arizona by four points in 2016.
A retired Air Force colonel who made history as the first woman ever to fly in combat, McSally had to first survive a conservative primary challenge.