Kamala Harris might trigger Trump's biggest vulnerability

• Donald Trump and his allies are already preparing for Kamala Harris' potential challenge.
• But the former president often crosses a line when he criticizes women.
• Democrats can only hope that Harris would provoke a similar reaction.

Democrats have long believed the best way to beat Donald Trump is to remind Americans was they turned against the former president in the first place. While she isn't yet his official opponent, Vice President Kamala Harris' mere presence could provoke such a reaction.

Trump has long executed a brutal playbook against his political opponents. He questioned Jeb Bush's energy, Marco Rubio's height, and Ron DeSantis' sincerity (Trump's allies went after DeSantis' eating habits.)

But when Trump deploys the same tactics against women, it often blows up in his face.

In 2015, Trump sparked one the first uproars against him after he said then-Fox News anchor Megyn Kelly had "blood coming out of her wherever" as he stewed over a debate question about his history of misogynistic comments. Later during the primary, former Hewlett-Packard CEO Carly Fiorina notched a breakout moment when asked how Trump insulted her looks.

"Women all over this country heard very clearly what Mr. Trump said," Fiorina said when asked about Trump insulting her appearance to a Rolling Stone reporter. After seeing an image of Fiorina on TV, Trump said, "Look at that face! Would anyone vote for that? Can you imagine that, the face of our next president?!"

Years later, Trump deeming former Secretary of State Hillary Clinton "a nasty woman" remains a badge of honor for Democrats.

Trump's tendency to follow Roy Cohn's admonition to hit back harder has only exposed him more when a woman confronts him.

In some cases, the exposure came with an actual cost, as columnist E. Jean Carroll can attest after she was awarded nearly $100 million in damages after Trump continued to attack her even after he was found liable for sexually abusing and defaming her.

Most recently, Trump mocked former UN ambassador Nikki Haley's name, labeled his former Cabinet official "a birdbrain," and taunted her husband, Michael, for being absent from the campaign trail despite the fact he was deployed at the time. Haley has since endorsed Trump.

Trump's former foes have turned his attacks into rallying cries, a response that Harris and her allies are likely to use. Even after the 2016 race, former Secretary of State Hillary Clinton continued to embrace Trump's insult that she was "a nasty woman."

Even some Republicans have called out Trump for crossing the line. More than 40 GOP lawmakers called out President Trump in 2019 when he attacked the four female members of the so-called "squad," saying they should "go back" to where they came from. All four Democrats, Reps. Alexandria Ocasio-Cortez of New York, Ayanna Pressley of Massachusetts, Rashida Tlaib of Michigan, and Ilhan Omar, were US citizens. Omar was born in Somalia, which she later fled as a refugee and then emigrated to the US.

"I am confident that every Member of Congress is a committed American. @realDonaldTrump's tweets from this weekend were racist and he should apologize," Rep. Mike Turner of Ohio, a Republican, wrote on Twitter at the time. "We must work as a country to rise above hate, not enable it."

Democrats have long run up the score with women, though Trump has improved his standing with them somewhat and even narrowed the gender gap in 2020. Before he dropped out, Biden had the smallest lead among women for a Democratic hopeful since 2004, according to The New York Times.

Trump seems far more focused on expanding his advantage with men, something Biden was able to cut into in 2020. The Republican National Convention leaned heavily into testosterone-fueled appeals, including wrestler Hulk Hogan doing one of his signature shirt rips and a keynote address by UFC President Dana White.

Still there were some nods to showing a different side of how Trump treats women. Arkansas Gov. Sarah Huckabee Sanders said during a convention speech that Trump reassured her when she was the subject of attacks as his White House press secretary.

"Sarah, you're smart, you're beautiful, you're tough, and they attack you because you're good at your job," Sanders said.