Although Harris doesn't talk much about her potential to become the first female president, the video shows the gender gap that has widened between her and Trump. Recent polls show that Harris is clearly ahead among women and Trump is clearly ahead among men.

Harris' opponents have used her gender throughout her campaign to question her qualifications. Trump said in July that leaders viewed Harris “like a toy” because of her looks, and his allies suggested that Harris' political success was due to policies of diversity, equity and inclusion.

Meanwhile, Trump's campaign has embraced an image of traditional masculinity and actively courted influencers and comedians popular with young men.

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Gender also underlies many hot-button issues influencing voters' decisions this election cycle, including abortion, in vitro fertilization, child care and transgender rights.

The campaign ad, created by Vote Common Good, a nonprofit progressive group that works to mobilize religious voters, sparked outrage from Trump and some of his allies.

Although the organization never paid to promote or broadcast the video, its executive director Doug Pagitt said the attention the video received online meant it tapped into an experience familiar to many households.

“So many people in the world I come from and the political world that follows believe that women's responsibility in voting is primarily not to have their own voice,” said Pagitt, a pastor and social activist. “It’s about reproducing what their husband tells them.”

In a telephone interview with Fox News on Saturday, Trump said he was “so disappointed in Julia Roberts” and that one day she would look back at the ad and “cringe.” He added that he didn't believe the video depicted a realistic marriage dynamic, calling it “ridiculous.”

“I mean, can you imagine a woman who doesn't tell her husband who she's voting for?” Trump said. “Even if you have a terrible, bad relationship, you will tell your husband.”

Fox News host Jesse Watters said on the show last week that if his wife did the same thing as the women in the ad, it would violate “the sanctity of our marriage.”

“If I found out that Emma went into the voting booth and pulled the lever for Harris, that's the equivalent of having an affair,” Watters said, a remark that led many online to call him out for his marital affair, which he admitted until 2018.

Conservative podcast host Charlie Kirk, founder of Turning Point USA, called the ad “disgusting” as he criticized the woman for “lying to her sweet husband who is probably going out of his way to make sure that she can lead a nice life and provide something for the family.”

Former House Speaker Newt Gingrich, R-Ga., joined the criticism Thursday, telling Fox News that Democrats are asking women to lie to their husbands: “What a completely amoral, corrupt, sick system they have Democrats developed?”

While some conservative men expressed disbelief and disapproval, many joined the discussion online, sharing their experiences with women secretly supporting Democrats in Republican households and saying they feared for the well-being of women whose husbands responded insist on controlling or monitoring their votes.

In recent months, Post-It notes have also been discreetly appearing in public bathroom stalls and on tampon boxes across the country, reminding women that no one can see whether they vote for Harris.

Several women involved in the grassroots campaign in more conservative areas told NBC News that getting involved in the sticky note campaign was a way for them to be politically active without facing backlash from the Republican-dominated areas where they live live, to deal with.

The controversy surrounding the ad has led some online users to draw parallels to Margaret Atwood's classic novel “The Handmaid's Tale,” which depicts a dystopian theocratic regime that forcibly categorizes women and strips them of their personal autonomy. Following the discourse, Atwood published a political cartoon of women entering a voting booth dressed as maids and removing their red uniforms as they exited.

For Pagitt, the angry reactions of some men online underscore the need for the video's message.

“They honored the holiness of a person on their ballot and turned it into a conversation about men taking ownership of the behavior of the women in their lives,” Pagitt said. “And I didn’t think you’d make our case for us. We are very grateful for that.”