The 30-second-clip, narrated by actor Julia Roberts, shows the couple arriving at a polling station wearing baseball caps featuring the American flag, a symbol often sported by Trump supporters.
The ad, financed by a religious nonprofit, has elicited fury in the Trump camp, with the former president calling it "stupid" and asking "Can you imagine a wife not telling her husband who she's voting for?"
In the ad, the wife exchanges knowing glances with another female voter, before filling in her choice for Harris.
"You can vote any way you want, and no one will ever know," the voiceover says, before the husband asks "Did you make the right choice?"
"Sure did, honey," the woman replies.
Unprecedented gender gap
On conservative Fox News, a host recently said his wife secretly voting for Harris would be "the same thing as having an affair," while former Republican House speaker Newt Gingrich said the Harris spot was an example of the depth of her camp's "corruption."
Anti-Trump political group The Lincoln Project aired a similar ad showing two upper-middle class men who assure each other their wives are voting for Trump. The women -- and other females at the voting precinct -- then fill in their ballots for Harris.
The videos, and the furious reaction from Trump supporters, illustrate two key facets of the US presidential campaign.
One is that Trump and Harris are truly fighting for every last vote, in what is perhaps the most down-to-the-wire presidential race in modern US history.
The other is that Harris is counting heavily on mobilizing women in the ultra-tight race that will see a gender gap in votes like never before.
According to a latest poll by NBC, there is a 34-percentage point difference between male and female intended voters.
Harris has a 16-point lead among women while Trump has an 18-point lead among men.
The unprecedented gap comes with Harris's campaign having leaned heavily on reproductive and abortion rights, following the Supreme Court strike-down of the federal right to the procedure in 2022.
Clooney surprise
More broadly, the election is a clash between the "traditional and kind of patriarchal masculinity" espoused by Trump and Harris's policies which are "less aligned with stereotypical gender roles," said Kelly Dittmar, a political science professor at Rutgers University.
Former Republican congresswoman Liz Cheney, who has stumped for Harris, is openly betting on "secret" votes for the Democrat.
"I think you're going to have, frankly, a lot of men and women who will go into the voting booth and will vote their conscience and will vote for Vice President Harris," said Cheney, who is the daughter of former vice president Dick Cheney.
"They may not ever say anything publicly but the results will speak for themselves," she said.
Former first lady Michelle Obama recently hammered home the point, reminding the female electorate: "If you are a woman who lives in a household of men that don't listen to you or value your opinion, just remember that your vote is a private matter."
The Harris campaign's quest for "secret" voters doesn't stop with women. The group that funded the Julia Roberts-narrated ad, Vote Common Good, recently released a second spot, this time featuring two male voters casting their ballots for her without telling their Trump-supporting buddies.
The ad is narrated by another star, George Clooney.
