It culminated in January 1993, when Harth and Houraney were visiting his Florida mansion, Mar-a-Lago, to finalize and then celebrate the beauty pageant deal with a party.

After business concluded, Harth and Houraney were on tour of Mar-a-Lago along with a group of young pageant contestants – Trump wanted to “see the quality of the girls he was sponsoring”, Harth recalled – when he pulled her aside into one of the children’s bedrooms.

“He pushed me up against the wall, and had his hands all over me and tried to get up my dress again,” Harth recalled, “and I had to physically say: ‘What are you doing? Stop it.’ It was a shocking thing to have him do this because he knew I was with George, he knew they were in the next room. And how could he be doing this when I’m there for business?”

Speaking as Republicans gathered in Cleveland to formally declare Trump as the party’s candidate in the November general election, Harth told how she had been very reluctant to talk after the sexual assault allegations resurfaced, “because honestly, it was painful for me to have to do it again. It was stressful, it gave me anxiety, it definitely wounded my marriage – it wasn’t the death knell, but it wounded it, it was stressful having to handle this.”

She recalled how Trump – who had just gone through a divorce from his first wife, Ivana, and was in a relationship with Marla Maples, who would become his second wife – pursued her and urged her to leave Houraney.

“Trump did everything in his power to get me to leave him. He constantly called me and said: ‘I love you, baby, I’m going to be the best lover you ever had. What are you doing with that loser, you need to be with me, you need to step it up to the big leagues.’

“He was constantly working on me during that time and that took a toll on me. But I moved on. I’m a forgiving type person, OK? I’m a Christian, I moved on.”

‘They tried to get me to say it never happened’

Trump’s decision to run for president brought the question to the fore for her once more. And initially, she said she was inclined to let bygones be bygones.

She concedes she even found herself getting excited at the thought that someone she knew so well was running for president.

A recent Trump rally she attended seemed to confirm her decision to lay low. “’Don’t worry about it,’ I said, ‘I’m not going to say anything bad, we’ve moved on, we’re friendly,’” Harth recalled in her interview with the Guardian.

When Trump thanked her and gave her a hug, she thought he wouldn’t say anything either.

The interaction, Harth said, reaffirmed her decision to stay quiet. That is, until she saw Trump dismiss media reports referencing her case as “meritless”, or worse.

After the New York Times ran a story in May this year about Trump’s history with women, including an account of Harth’s story, Trump’s campaign even reached out to her to pressure her to take back her account, she told the Guardian on Tuesday.

“His office – and I have it on my voicemails that he called, that they called – they asked me to recant everything when the New York Times article came out. They were trying to get me to say it never happened and I made it up. And I said I’m not doing that,” recalled. Trump’s office denied this.

She was further upset by an interview Trump’s daughter Ivanka gave in the wake of the New York Times article saying her dad is “not a groper”.

“I understand that the girl wanted to defend her dad, being it’s her dad,” she said, “but what did she know? She was 10 years old! She was 10 years old at the time. She didn’t know what her father was about, what he was doing, how he was acting.”

Such statements felt defamatory to Harth, adding insult to injury. That’s when she hired attorney Lisa Bloom to demand that Trump retract his statements that are, as Bloom put it, “effectively calling her a liar”.

“Jill is very clear that she is not a liar,” Bloom said. “And her reputation is important to her. And her living a life free of this kind of stress is important to her. So we’re calling on not only Mr Trump, Ivanka Trump, too.”

The renewed controversy comes as Trump prepares to give his keynote speech in Cleveland on Thursday. It also comes as Roger Ailes, the chairman and CEO of Trump-friendly Fox News, is in the process of being ousted following a sexual harassment suit filed by a former anchor.

When Trump’s office was asked to respond to Harth’s allegations, they highlighted her inconsistency about her views on Trump, forwarding emails from 2015 and as recently as January 2016in which she expressed friendly feelings about Trump and even asked about a job helping to do his campaign trail makeup.

As Harth wrote in an August 2015 email forwarded by Trump’s campaign: “I also would like to show my support for Donald and his campaign. I am offering my services to do his grooming and getting him perfectly camera ready for photos and Hi-Definition TV. He knows better than anybody how important image is.”

In another email from October 2015, she praised Trump for “doing a tremendous job of shaking things up in the United States” and added: “I am definitely Team Trump!”

Harth said those emails were written months before Trump called her integrity into question. She also defended her action, as a businesswoman who has never been too proud to look for help where she needs it, even if it smacks of opportunism.

Meanwhile the fact that Trump has an army of staffers and family defending him is party of what inspired her to speak out, she said.

“Nobody was defending me, that’s why I’m talking,” Harth said. “You can believe it or not, but I went through hell and I still have to relive this again. And I just, I’m horrified that I have to think about this again.”

Michael Cohen, executive vice-president and special counsel to Donald Trump, responded by email to a Guardian request for comment, saying: “It is disheartening that one has to dignify a response to the below absurd query. Mr Trump denies each and every statement made by Ms Harth as these 24-year-old allegations lack any merit or veracity.

“Hope [Mr Trump’s spokeswoman Hope Hicks] will forward to you under separate e-mail ,a series of e-mails documenting Ms Harth’s support of Mr Trump, the race for the White House as well as seeking a job opportunity with the campaign.”

In an earlier phone call, Cohen said Harth had “massive credibility issues”.

Speaking in Cleveland at the Republican national convention on Wednesday, Roger Stone, a veteran strategist and longtime Trump adviser, dismissed the allegations, saying: “I have an excellent bull***t detector.”

Stone added: “A verbal agreement is entirely unprovable … So it’s more he said, she said. Sure sounds like bull***t to me.”

Such responses from the Trump camp aren’t new and neither is the lawsuit, which Harth brought forward in 1997. She dropped it weeks later after Trump settled an outstanding business lawsuit from her partner Houraney claiming he broke contract backing out of the American Dream festival. (Houraney sued for $5m but settled with Trump for a smaller, undisclosed amount.)

Houraney met Harth when she was still in high school and though he didn’t witness any of the alleged incidents with Trump, aside from that first meeting in Trump Tower, Houraney has never doubted her. “I know they’re all true,” he said of the allegations. “I knew her way too long to think she could make up stuff like that, It wasn’t in her. She wasn’t capable of making up the things she said in that thing.”

Harth told the Guardian she expected very little from Trump. “I’m not going to get an apology from him. That would be nice, but he – I don’t fully expect one. But he really should have been taught, if you don’t have anything nice to say don’t say anything, OK? Don’t call me a liar.

“He didn’t have to say anything. For once, he should have closed his mouth. He didn’t have to comment. We were on great – not great, I’ll take that back – we were on good terms, friendly terms. He didn’t – he started this. What is happening now is of his own making, OK? I was quiet.”