Days after winning elected office, a Republican politician in Indiana pleaded guilty to trying to sexually assault his daughter in Las Vegas and now must resign his position.

John Jessup, the commissioner of Hancock, Indiana, was charged in Nevada in June in connection with a sexual assault that occurred in January, reported the local Greenfield Daily Reporter newspaper and KLAS.

But he remained in office as a county commissioner, ran for a seat on the Hancock council, a distinct elected body, and emerged as one of three victors after collecting about 15,000 votes.

Records show Jessup, 49, pleaded guilty in Nevada court on 13 November to attempted sexual assault, which is a kind of felony that can carry multiple years in prison, according to state law.

Indiana prohibits convicted felons from serving in state or local elected offices, though a decisive majority of its voters on 5 November helped vault Donald Trump to a second US presidency just months after a New York jury convicted him on felony charges of criminally falsifying business records.

Therefore, Jessup must resign – unlike Trump, who has also faced multimillion-dollar civil penalties for a rape allegation that a judge determined to be substantially true.

Jessup on Monday told the Guardian that he must fill out certain paperwork before he can step down. The county council chair had mailed him those papers, but they had not immediately arrived, said Jessup, who is awaiting a sentencing hearing tentatively scheduled for April.

According to what Jessup told the Daily Reporter, he was prepared for prosecutors to argue that he deserves between eight and 20 years in prison. Jessup reportedly said his attorneys were going to seek a sentence of probation.

“It’s been my greatest honor serving the people of Hancock county and I’m deeply, deeply ashamed and profoundly sorry for the shame that I brought to the county,” Jessup told the Daily Reporter.

An affidavit obtained and reported on by the outlet said Jessup’s criminal charges came after he flew to Las Vegas with a woman in January.

The affidavit did not identify the woman. But in an article on Tuesday, the Daily Reporter wrote that Jessup was charged with assaulting his youngest daughter, Rachel, on a trip to Las Vegas intended to celebrate her 21st birthday.

“I never dreamed it would have ended up the way it did,” Rachel Jessup reportedly told the outlet.

Multiple witnesses allegedly told authorities that John Jessup got Rachel intoxicated. Allegedly, as Jessup repeatedly said the slogan “what happens in Vegas stays in Vegas”, she became so intoxicated she needed a wheelchair to get back to her hotel room.

There, she said she recalled showering while clothed – and her next recollection was waking up naked as Jessup sexually assaulted her, authorities wrote in the affidavit cited by the Daily Reporter.

The woman reported the assault to police in just a few days, and authorities arrested him in Indiana in June before extraditing him to Nevada. According to the Daily Reporter, during an interview with investigators, Jessup acknowledged that he “fucked up” – and spoke of suicide – yet also said he had not done anything criminal.

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Jessup posted a $100,000 bond to await the outcome of the case against him under house arrest in the Las Vegas area.

In a statement to the Indiana news outlet WXIN, a Republican party official in Hancock county denied that her organization had any role in Jessup’s case “until the legal process concludes or he resigns”.

“Mr Jessup decided to keep his name on the ballot after charges were filed,” Janice Silvey, Hancock county Republican party chairperson, said in a statement. “He later verbally and via text committed to resigning if elected.”

Silvey added that the local Republican party would arrange a caucus to fill Jessup’s position once his resignation takes effect.

Rachel Jessup, now 22, told the Daily Reporter she was disappointed voters elected her father despite the charges against him.

She reportedly said she spoke out publicly because “I want it known it’s OK to come forward, and while it’s hard, it’s good to share what happened”. She also discussed her plans to pursue a graduate-level degree in social work.

Hancock county is part of a region that includes Indianapolis, the state capital. It has a population of about 80,000.

Information and support for anyone affected by rape or sexual abuse issues is available from the following organisations. In the US, Rainn offers support on 800-656-4673. In the UK, Rape Crisis offers support on 0808 500 2222. In Australia, support is available at 1800Respect (1800 737 732). Other international helplines can be found at ibiblio.org/rcip/internl.html