With a decisive loss for Garcia on Tuesday and an Associated Press-reported victory for Republican secretary of state candidate Steve Gaynor - his opponent, Katie Hobbs, has not conceded - Sinema's contest is one of the last opportunities for Arizona Democrats to score a statewide office.
The picture was brighter for the state's Democrats in Congress, where Democrat Ann Kirkpatrick was elected to the Tucson-area swing district seat vacated by McSally and Democrats held all their other four seats, giving them a majority of the state's nine-member U.S. House delegation.
Sinema and McSally are battling to fill the seat being left open by outgoing Republican Sen. All three are running to replace retiring Senator Jeff Flake. But many ballots known as "late earlies" arrive in the mail on Election Day, in the few days leading up to it or are hand delivered by the voters themselves. She has tried to rally Republican voters by emphasizing her military background as the first USA female combat pilot while touting her support for the president's tax cut and other parts of his agenda.
In response, McSally criticized Sinema over her shifting views, contending she was still a closet liberal who disrespected the military. As of Wednesday morning, Republicans have secured 16 and Democrats 13.More news: Midterms 2018: Firsts for women in the US House
McSally also accused Sinema of treason for an offhand comment in a 2002 radio interview with an anti-war talk show host who suggested hypothetically he might join the Taliban.
That appeal, and her perceived independent streak, is what drew Matt Winter to volunteer for Sinema. "We think Martha McSally leads in that vote by about 949 votes, based on what we know about those counties and the votes counted so far".
Candidates for Arizona's U.S Senate seat are only separated by one percentage point.
People gather for the Arizona Democrats Election Night party at the Renaissance Hotel Downtown in Phoenix, Nov. 7, 2018.
If she wins, her campaign could become a centrist blueprint for Democrats eager to win in deep-red Republican strongholds. But Democrats have repeatedly hoped the state's growing Latino population and influx of more educated professionals would make it competitive. However, as the Arizona Republic explains, those are the results that came in yesterday throughout the day.