Following multiple defeats in the Republican presidential primary, including in her home state of South Carolina, Nikki Haley suspended her bid for the Republican presidential nomination on March 6, 2024.

Barring unforeseen events, Donald Trump will be the GOP candidate in November’s election.

Haley’s failure to pose a more serious challenge to Trump may be puzzling to some. After all, she was a formidable candidate with notable political experience in both federal and state government. She had outlasted prominent Republican officials, including Florida Gov. Ron DeSantis, former New Jersey Gov. Chris Christie and South Carolina Sen. Tim Scott, in the GOP primary.

And Trump has serious political liabilities. Although he is wildly popular among Republican primary voters, Trump’s support is much weaker among likely general election voters. Trump’s unpopularity served as a drag on Republicans’ performance in the 2018 midterm elections, likely cost him a winnable presidential election in 2020 and contributed to Republicans’ underperformance in the 2022 midterms.

He also faces indictments on 91 state and federal charges ranging from plotting to overturn the 2020 election to withholding classified documents in his home in Florida. And observers, including Haley, have raised serious questions about his age, physical fitness and mental acuity.

Given her strengths and Trump’s vulnerabilities, why did Haley’s primary campaign fall flat? Of course, part of the reason is Trump’s unique appeal with Republican primary voters. Over the past eight years, Trump has forged a distinctive bond with his voters that leads them to overlook his significant political weaknesses.

But sexism is also an important part of the explanation.

Trump’s history of sexism

Back in 2016, Trump frequently made sexist remarks directed at Democratic presidential nominee Hillary Clinton. He called her a “nasty woman,” said she does not have the “presidential look” and contended that Clinton was “playing the woman card.”

Research shows that voters with more sexist attitudes were more likely to support Trump in 2016.

Eight years later, Trump employed a similar sexist playbook, questioning Haley’s qualifications, commenting on her appearance, characterizing her as “overly ambitious” and mocking her for having an absentee husband. Haley’s husband is in the South Carolina National Guard and currently deployed overseas.

We are political scientists who field and analyze public opinion surveys to better understand Americans’ attitudes. Using evidence from our recent national poll, we can examine how sexism influenced Republicans’ preferences in the 2024 Republican primary.

We first asked Republican respondents whom they would favor in the Republican presidential primary. Next, we measured sexist attitudes by asking respondents a series of questions about their prejudice, resentment and animus toward women. These attitudes are collectively known as “hostile sexism.” We also collected information about Republicans’ demographic characteristics, political attitudes and beliefs about the economy.

Familiar foe of sexism in the electorate

We find that individuals who supported Trump display much higher levels of sexism than those who favored Haley. Only 27% of Haley supporters agreed with the statement that “women seek to gain power by getting control over men,” but 38% of Trump voters agreed.

Likewise, when asked whether “women are too easily offended,” 52% of Trump supporters agreed, while 42% of those supporting Haley did so.

Finally, when provided with the prompt that “women exaggerate problems they have at work,” 37% of Trump voters agreed while only 25% of Haley voters expressed this view.

Next, we undertook an analysis that examined how sexist attitudes related to support for Trump relative to Haley, while taking into account demographic characteristics, political identities and views on the national economy.

This analysis confirmed that, even after taking into account these factors, individuals with more sexist attitudes were more likely to favor Trump over Haley.

In her challenge to Trump for the Republican presidential nomination, Haley, like female candidates across the partisan divide, contended with the familiar foe of sexism in the electorate.

While much is uncertain about the upcoming election, the nation will almost certainly continue to wait for its first female president.

The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.