The photo could have been taken at any prom or sorority formal. Girls with long hair and fancy dresses, their arms draped around one another’s shoulders, smiling wide.

Just five seconds into the campaign ad, a narrator makes clear that the image had not captured a celebratory kind of night.

“It was 2004,” says Claire Russo, 40, a former combat veteran running for Congress in Virginia. “I was attending the Marine Corps Ball when I was drugged and raped by a superior.”

Ms. Russo, a Democrat, spent the next few years trying to get her day in court, she says. After the Marine Corps decided not to charge her superior and denied her request to transfer to another base, she took her case to the San Diego district attorney’s office. Her attacker pleaded guilty to sodomy before his civilian trial began and was sentenced to three years in prison. After serving about half of his jail time, he received an honorable discharge from the Marines, according to reports.

Now, Ms. Russo is placing her assault and the battle that followed at the center of her campaign to be the Democratic candidate in a southern Virginia congressional race. Her television ad is the first to feature a candidate’s personal recollection of rape, according to political strategists and organizations that track political ads. Set to air on broadcast and cable networks starting this week, the spot is expected to make up a major portion of her advertising, according to her campaign.

“I have been someone whose voice has been silenced. I have been someone who was denied justice,” Ms. Russo said in an interview. “It is important to show the voters in this district that we can win and that we can take power back.”

As she leans into her history as a survivor of sexual violence, Ms. Russo is aligning herself with a powerful element of the Democratic Party’s identity in the #MeToo era: that it is the party for women, by women. Over the last three years, many Democrats expressed a zero-tolerance stand on sexual misconduct.

Though occasionally divisive within the party, that position has allowed Democrats to draw a clear contrast with President Trump. Frustration over Mr. Trump’s history of misogynistic remarks and allegations of sexual violence, as well as the treatment of Christine Blasey Ford during Justice Brett M. Kavanaugh’s confirmation hearings in 2018, helped Democrats win control of the House in the midterm elections — largely on the support of suburban women.

But the party’s position grew far more complicated in March, when Joseph R. Biden Jr. was accused of sexual assault by Tara Reade, a former Senate aide. As Democrats have rallied to the defense of their presumptive presidential nominee, Republicans are seizing on the issue, slamming the party as hypocritical for continuing to support Mr. Biden.

Public polling has found that a significant number of Americans of all political stripes are uncertain about whom to believe regarding Ms. Reade’s allegations. Even so, some experts say, the charges of hypocrisy could be weaponized to undermine the Democratic Party’s credibility on gender issues — particularly in swing suburban areas with independent voters who are likely to be a key voting bloc in November.

In a PRRI poll conducted just before the 2018 elections, political independents were 10 percentage points more likely to say the Democratic Party was doing a good job at confronting sexual harassment and assault than they were to say the same about the Republican Party. Still, both parties got negative marks from a majority of independents on these topics.

If in 2018, the political calculus around a discussion of sexual assault seemed straightforward for many in the Democratic Party, this year is quite different. Voters say they don’t know what they believe on the Reade allegation, which could have an impact if Republicans continue to raise it. And, if she wins her competitive primary, Ms. Russo will be testing the country’s evolving attitudes in a challenging district for Democrats.

Running from the North Carolina border to the outer reaches of the Northern Virginia suburbs, Virginia’s Fifth Congressional District was last won by a Democrat in 2008. In 2016, President Trump won the area by 11 points and last year, Representative Denver Riggleman, a Republican, won by nearly seven points even as other areas of the state flipped blue.

Already, Republican Party committees have blasted Democratic members of Congress regarding the Reade allegation, suggesting that they are operating with a different standard than the one they used for accusations of sexual assault against Justice Kavanaugh. Polling shows that a majority of Republicans believe Ms. Reade’s allegation.

The Republican strategist Mike Davis, who heads the Article III Project, a group focused on defending conservative judges, said he planned to use Ms. Reade’s allegation to sway independent voters toward Republicans in the presidential and congressional races.

“These #MeToo mobsters have turned into contortionists,” said Mr. Davis, a former Republican aide who was a central figure in the confirmations of Justices Neil M. Gorsuch and Kavanaugh. “Democrats are more concerned about power than they are about sexual assault survivors and that’s always been the case.”

Ms. Russo said she was supporting Mr. Biden, pointing to the difference between how the presumptive Democratic presidential nominee handled Ms. Reade’s allegation and how Mr. Trump has responded to claims of sexual assault and misconduct from more than a dozen women. Mr. Biden has called for the release of documents related to Ms. Reade’s employment in his office and emphasized that survivors “have a right to be heard.”

“You can care about fixing our system and care about victims and support Joe Biden,” Ms. Russo said.

In a Quinnipiac University poll released this week, only half of Democrats said they believed Mr. Biden, with four in 10 saying they needed to hear more about the accusation. Among independent voters, slightly more believe Ms. Reade than Mr. Biden and nearly half said they needed to learn more.

In a Monmouth University poll this month, when asked to pick whom they believed more, over a third of independent voters said they couldn’t choose.

“The large numbers of ‘don’t know,’ especially if you have to volunteer it, is huge,” Fred Conrad, a public opinion expert at the University of Michigan, said in an interview. “That’s a red flag — that this is just not something about which there’s agreement, even within political ideologies.”

Some recent surveys have shown Mr. Biden’s favorability slipping somewhat — though not drastically — in the months since Ms. Reade accused him of attacking her during her time working for his Senate office in the 1990s.

Tresa Undem, a pollster who has studied the intersection of politics and gender issues since before the #MeToo movement, said her research suggested that a charge of hypocrisy had the potential to taint not only Mr. Biden but the Democratic Party in general — particularly among independent female voters.

“If it keeps coming up, and in these down-ballot races if the Republicans use it as an attack, yes, it’s a big deal,” Ms. Undem said. “Among independent women, it has the potential to have a lasting impact, not just in terms of enthusiasm toward Biden or motivation to vote, but feelings toward the Democratic Party more broadly. What the Democrats stand for.”

But in a primary campaign that’s largely playing out on iPhones and TV screens, with candidates competing in a crowded field amid a pandemic, the advantage from a buzzy ad may outweigh possible political vulnerabilities.

Ms. Russo’s first political ad introduced her to the sprawling district, and made passing reference to her sexual assault, sandwiching a description of herself as a “survivor” between “Democrat,” “mom” and “Marine.”

She said the assault and the fight that followed are not the reasons she decided to run for Congress, pointing to her military service in Iraq and Afghanistan, work in national security and her three young children as all part of her motivation. The experience of battling a big institution like the military to take her case seriously, though, isn’t far from her thoughts in this campaign.

“I saw that serving my country was as much about fighting for justice and giving victims the strength to have their voices heard, as it was about targeting insurgent networks in Falluja,” she said.

Ms. Russo trails her major primary rivals in fund-raising dollars but, in February, picked up the endorsement of Emily’s List, which supports female Democrats. She will face two men, including a fellow Marine veteran, in the party primary on June 23.

Credit…Sarah Silbiger/The New York Times

Though Ms. Russo’s ad is breaking new ground, women in politics have begun speaking candidly about these subjects. In 2018, two Democratic congressional candidates, one in Illinois and another in Florida, produced ads about their experience with abuse and assault — stories of survival presented as part of the experience they would bring to office. And elected officials have also shared painful parts of their past.

In an emotional speech on the floor of the Michigan State Senate in 2013, Gov. Gretchen Whitmer, Democrat of Michigan, revealed that she had been sexually assaulted several decades ago. Last year, Senator Joni Ernst, a Republican from Iowa, said that she was raped in college after court documents alleging physical and emotional abuse by her ex-husband became public.

A few months later at an event at the U.S. Naval Academy focused on campus sexual assault, Senator Martha McSally, a Republican from Arizona, talked about her rape while in the Air Force.

The politicians recounting their own stories of sexual violence come from both parties, a clear demonstration that assault is not partisan.

But whether people believe an assault claim usually has a lot to do with politics. For instance, most Republicans generally told pollsters they did not believe Dr. Blasey’s allegations against a Trump nominee to the Supreme Court. Today, they are far more likely to say that they believe Ms. Reade’s allegation against the presumptive Democratic nominee.

Independents — including voters Ms. Russo might hope to pick up in Virginia’s open primary — say they don’t know what to believe.