The Democratic Party's leading candidate, three-term incumbent Rep. Kyrsten Sinema, faces a relatively weak field, while McSally and her Republican opponents are expected to wage a bruising Republican contest until the state's late August primary elections. Jeff Flake has won only half the battle.
"I told Washington Republicans to grow a pair of ovaries and get the job done", she says in the video, where she admits to "talking like a fighter pilot".
While her formal announcement will come in a tour across the state Friday, her campaign released a video ahead of time showing her as someone not afraid to take on the establishment, Sharia law, and who will push for border security. She has spent three years representing Arizona's 2nd Congressional District, which is split almost evenly between Republicans, Democrats and independents.
"I absolutely refuse to bow down to Sharia law", McSally says, after a narrator discusses her successful fight against a USA military policy that required women to wear head-to-toe garb in Saudi Arabia.
One interesting feature of this ad is how McSally recasts her first moment of real fame during her military career, when she sued the Pentagon to strike down its policy of making off-duty servicewomen posted to Saudi Arabia wear the abaya, the long robe insisted upon by Saudi religious authorities.
Beyond failing to endorse Trump's candidacy, McSally has also been critical of Trump's words and actions during the first year of his presidency.
"Like our president, I'm exhausted of PC politicians and their BS excuses", McSally said in her hard-hitting announcement video, released Friday, that also highlighted her career as an Air Force fighter pilot and her eight-year fight to end a military policy requiring female soldiers in certain Muslim-majority countries to wear robes over their military uniforms.
Trump has made no official statement since McSally made the announcement. But she sidestepped a follow-up question on what she thought about his comments Thursday labeling Haiti and African countries "shitholes". "That's just not how leaders carry themselves", she said at the time.
In an interview, she refused to say whether she supports a pathway to legal status for millions of other immigrants in the country illegally.
The 9 a.m. event, while held on private property, was advertised as open to the public. "There should be no sanctuary for anyone breaking our laws and harming our people".
One of them was congressional candidate Mary Matiella, who held the civilian equivalent rank of a four-star general when working for the Department of Defense. "It is who he is", she said.
"I'm only responsible for myself", McSally said.
A Senate run by McSally has been hinted at for months.
Ms. McSally, Arizona Republican, now represents Arizona's second congressional district, which stretches from Tucson to part of the U.S. -Mexico border.
So far, only one Republican has stepped up to run in CD2 - Lea Márquez Peterson. "And McSally has appeared on Fox News to sing the president's praises".
Pima County Supervisor Ally Miller briefly flirted with the idea of running in the GOP primary for CD2, but ended speculation Friday by telling the Star she had decided against it.
Nowicki is The Republic's national political reporter.