The confirmation of Brett Kavanaugh to the US supreme court was meant to be a crowning achievement for Donald Trump and Republicans, as they prepare to defend their congressional majority in what is expected to be a challenging midterm election in November.

But a sexual assault accusation against the judge has thrown his confirmation into turmoil – and injected an element of political peril into an already volatile campaign season, less than seven weeks before election day.

Republicans have scheduled a high-stakes public hearing before the Senate judiciary committee next week, with both Kavanaugh and Christine Blasey Ford, who accused him of sexually assaulting her at a high school party in the 1980s, when they were both teenagers. It is an allegation he has categorically denied.

Though it remains unclear whether the session will take place, and whether Ford will appear in person, the possibility recalls the 1991 supreme court confirmation hearing of Clarence Thomas, who was accused of sexual harassment by a law professor, Anita Hill. The spectre of Hill being questioned on national television by an all-male judiciary panel enraged women and led to a banner election year for female candidates, known as the “Year of the Women”, in 1992.

Next week’s hearing would take place in a new era of female political activism, after hundreds of thousands of women marched in protest against Trump and the #MeToo movement that has energized Democratic women to run for office in record numbers.

“Republicans are in a lot of trouble with suburban women anyway and I can’t see how any of this helps,” said Liz Mair, a Republican strategist.

But she said a lot depends on what happens in the coming days. Powerful testimony from Ford or Kavanaugh would shape public perception and the political fallout.

“At the end of the day, if she testifies that’s going to be a very different equation than if she refuses to do it,” Mair said.

The supreme court is one the strongest issues for Republicans and played an important role in consolidating evangelical and conservative support for Trump in 2016. But the decades-old allegation threatens to undermine the issue for Republicans in close races where suburban women and independent voters play a decisive role.

Republicans are treading carefully as they attempt to defend Kavanaugh without appearing to attack Ford’s credibility and reinforce the impression that their party doesn’t take seriously allegations of assault within its ranks.

After Ford went public with her claims, several Republican senators called on the committee to delay a vote to allow for a public hearing. The Senate judiciary chairman Chuck Grassley has said Ford “deserves to be heard” and is negotiating with her legal team on the terms of her testimony.

Trump, who has attacked his own accusers as “liars”, had been uncharacteristically restrained in his response to the allegation. He defended Kavanaugh but avoided casting doubt on Ford’s account. At least, until Friday, when his tone changed.

In a series of tweets he questioned why Ford hadn’t gone to the police if the attack “was as bad as she says”. He called Kavanaugh a “fine man with an impeccable reputation who is under assault by radical left wing politicians who don’t want to know the answers”.

Senator Susan Collins, seen as a crucial Republican vote on his nomination, said she was “appalled” by the president’s tweets, adding “we know allegations of sexual assault are one of the most unreported crimes that exist”. On Twitter, people shared their stories of why they did not report sexual crimes against them, under the hashtag #WhyIDidntReport.

Trump’s comments compound remarks made by other Republican lawmakers and his son that have drawn criticism for minimizing or mocking Ford’s assault allegation.

“Did y’all hear this latest late-breaking news from the Kavanaugh hearings?” the South Carolina congressman Ralph Norman said in a debate this week. “Ruth Bader Ginsburg [the 85-year-old supreme court justice] came out that she was groped by Abraham Lincoln.”

Earlier this week, Donald Trump Jr, Trump’s eldest son, posted a meme on his Instagram account that likened Ford’s claim to a schoolyard crush. Senator Jeff Flake, a Republican who has clashed frequently with the president, called the post “sickening”.

There are political risks for Democrats, too. Many Republicans are frustrated by the timing of the allegation in the final stages of his confirmation process and view it as an “11th-hour” ploy to obstruct the president’s nominee from reaching the supreme court.

A lengthy delay could push the process into November, when the Republican majority in the Senate could be at risk.

“Both parties are on a knife’s edge here and either side could make a major mistake on how this is handled,” said Kevin Sheridan, a Republican strategist. “We don’t know yet who will come out on top.”

Complicating the picture is Kavanaugh’s deep unpopularity. A new NBC News/Wall Street Journal poll found that more Americans oppose his nomination than support it after the allegation emerged. Opposition rose nine points since last month, with women, independents and seniors driving the shift, according to the survey.

Jennifer Duffy, a senior editor at the nonpartisan Cook Political Report, said the confirmation battle could end up motivating Republicans, especially if they feel Kavanaugh has been treated unfairly by Democrats.

“Republican voters care about the supreme court and regardless of whether they believe Ford, the idea that Democrats have politicized her story is starting to really fire up the GOP base,” she said in an email.

She added that Democrats were already galvanized and invested in turning out in November.

“How much more can that base expand,” Duffy said. “In other words, how much more of a bump can they get, particularly among women?”

At a rally in Las Vegas on Thursday night, Trump praised his supreme court nominee as the crowd roared back in support and chanted is name: “Kavanaugh!”

The following morning, Mitch McConnell, the Senate majority leader, urged evangelical activists at the Values Voter conference in Washington to “keep the faith”.

“In the very near future, Judge Kavanaugh will be on the United States supreme court,” he predicted, promising that the Senate would “plow right through”.



