"As much as I don't want another four years of Obama's policies, I can't look my children in the eye and tell them I voted for Donald Trump," Bradshaw told CNN. "This is a time when country has to take priority over political parties. Donald Trump cannot be elected president."
The move comes after days of conflict between Trump and the family of a fallen U.S. soldier. The GOP nominee chastised Gold Star mother Ghazala Khan and her husband following their poignant Democratic National Convention speech -- an antic that sent Bradshaw over the edge.
"Every family who loses a loved one in service to our country or who has a family member who serves in the military should be honored, regardless of their political views. Someone with the temperament to be president would understand and respect that."
Bradshaw has been a registered Republican for decades, working most notably for Jeb Bush during his time as governor of Florida, as well as on his father's 1988 presidential campaign. She more recently helped author the "autopsy" report after the party's defeat in the 2012 presidential election.
Despite that history, she deems Trump, who she labeled "a total narcissist -- a misogynist -- a bigot," was too much to bear, saying "if and when the party regains its sanity, I'll be ready to return."
See more of the Khan family at the Democratic convention:
Slain vet Humayun Khan and his family
Slain vet Humayun Khan and his family
Khizr Khan, whose son, Humayun S. M. Khan was one of 14 American Muslims who died serving in the U.S. Army in the 10 years after the 9/11 attacks, offers to loan his copy of the Constitution to Republican U.S. presidential nominee Donald Trump, as he speaks while a relative looks on during the last night of the Democratic National Convention in Philadelphia, Pennsylvania, U.S. July 28, 2016. REUTERS/Mike Segar
Captain Humayun Khan, died while serving his country in 2004.
(Photo credit Khizr M. Khan)
Khizr Khan walks off stage after speaking about his son US Army Captain Humayun Khan who was killed by a suicide bomber in Iraq 12 years ago, on the final night of the Democratic National Convention at the Wells Fargo Center, July 28, 2016 in Philadelphia, Pennsylvania. / AFP / Robyn Beck (Photo credit should read ROBYN BECK/AFP/Getty Images)
Khizr Khan, who's son Humayun (L) was killed serving in the U.S. Army, speaks at the Democratic National Convention in Philadelphia, Pennsylvania, U.S. July 28, 2016. REUTERS/Lucy Nicholson
Khizr Khan, father of Humayun S. M. Khan who was killed while serving in Iraq with the US Army, speaks during the fourth and final day of the Democratic National Convention at the Wells Fargo Center on July 28, 2016 in Philadelphia, Pennsylvania. / AFP / Nicholas Kamm (Photo credit should read NICHOLAS KAMM/AFP/Getty Images)
PHILADELPHIA, PA - JULY 28: Khizr Khan, father of deceased Muslim U.S. Soldier Humayun S. M. Khan, holds up a booklet of the US Constitution as he delivers remarks on the fourth day of the Democratic National Convention at the Wells Fargo Center, July 28, 2016 in Philadelphia, Pennsylvania. Democratic presidential candidate Hillary Clinton received the number of votes needed to secure the party's nomination. An estimated 50,000 people are expected in Philadelphia, including hundreds of protesters and members of the media. The four-day Democratic National Convention kicked off July 25. (Photo by Alex Wong/Getty Images)
Khizr Khan, whose son Humayun S. M. Khan was one of 14 US Muslims who died serving the United States in the ten years after 9/11 speaks during the final day of the 2016 Democratic National Convention on July 28, 2016, at the Wells Fargo Center in Philadelphia, Pennsylvania. / AFP / Robyn BECK (Photo credit should read ROBYN BECK/AFP/Getty Images)