For GOP Rep. Duncan Hunter, getting re-elected next year is the least of his concerns. Right now, he has to be worried about whether he will make it to the November 2020 ballot at all.

The San Diego County congressman is scheduled to go to trial in federal court in September on 60 felony counts involving alleged misuse of $250,000 in campaign funds. Although by law he could remain in office even if convicted, a guilty verdict would probably end his political career quickly.

He’s currently in political limbo. Hunter still holds his seat, but the GOP leadership in the House has stripped him of all his committee assignments.

Hunter has called the August 2018 indictment nothing more than a political attack by the Justice Department, which he described in a TV interview as “the Democrats’ arm of law enforcement.” But in recent weeks, prosecutors have tightened the screws on Hunter by allowing his wife, Margaret Hunter, to plead guilty to a single corruption charge after she agreed to cooperate with authorities.

In a June 24 court filing, prosecutors said the trial would include testimony about campaign cash that the congressman spent engaging in “intimate personal activities unrelated to Hunter’s congressional campaign or duties as a member of Congress” with five women, including three lobbyists, a GOP staff member and a woman who worked in his Washington, D.C., office.

“Hunter’s intimate relationships furnished part of his motive to embezzle from his campaign,” prosecutors said. “Carrying out all these affairs did not come cheap — Hunter spent thousands of dollars treating women to meals, drinks and vacations, and traveling to and from their homes.”

It could be an attempt by prosecutors to show Hunter the potential personal and political costs of a high-profile trial and entice him into a plea deal, said Laurie Levenson, a former federal prosecutor who is now a professor at Loyola Law School in Los Angeles.

Even when prosecutors have a strong case, a plea deal often works out best for both parties, she said. The government gets a quick, guaranteed result and the defendant usually gets less prison time.

Hunter’s attorneys complained that the government filed the motion “to publicly embarrass Mr. Hunter with evidence that reflects poorly on his character” and for the purpose of “publicizing Mr. Hunter’s infidelity.”

That’s unfair, they argued, because the congressman’s friendships “often blur the line between personal and professional, which is a widespread occurrence in modern politics.

“However unpopular the notion of a married man mixing business with pleasure,” Hunter’s relationships with the five women “often served an overtly political purpose,” the attorneys added.

Details of Hunter’s alleged affairs, along with testimony by the women and others involved, are likely to be part of any trial, Levenson said.

Rumors already are circulating that Hunter is looking to make a deal where he would plead guilty to at least some of the felony charges and resign his seat in Congress, clearing the way for a special election before November 2020.

“I’ve been told by various sources to expect a special election. We’ll have to wait and see,” Democrat Ammar Campa-Najjar, who lost a tight race to Hunter in last year and is planning for a rematch, said in a campaign email.

In an interview, Campa-Najjar said he is ready for anything.

“Everything is a rumor in politics until it happens,” he said. The 2020 race isn’t about Hunter, “but about me telling my story, what I want to do for the district.”

Hunter’s 50th Congressional District, which includes the San Diego suburbs, much of the county’s rural area and a small piece of Riverside County, is strongly Republican. Donald Trump defeated Hillary Clinton there in 2016, 55% to 40%.

In November, Hunter edged Campa-Najjar, 52% to 48%, his tightest race since first being elected to the House in 2008. Some Democrats would like to see the GOP incumbent on the ballot next year, figuring a challenger would have a better chance against a politically wounded Hunter than another Republican.

Don’t count Campa-Najjar in that number.

“I’ll be happy if (Hunter) is gone because if will allow us to focus on what’s important to the district,” he said. “You think he’d do the right thing for himself and the district and resign, because now he’s split between being a congressman and trying to stay out of jail.”

A number of Republicans already are set to challenge Hunter in the March primary and run for his seat in a special election if he resigns. Sam Abed, mayor of Escondido, Bill Wells, mayor of El Cajon (San Diego County), Matt Rahn, mayor of Temecula (Riverside County), and Larry Wilske, a retired Navy SEAL, all have filed papers to run against Hunter.

None of those names worries Campa-Najjar. “I have the resources, I have the name ID and I have the grassroots support,” he said.

Democrats hoping to see a Hunter-Campa-Najjar rematch should be careful what they wish for, said Thad Kousser, a political science professor at UC San Diego. He noted that Hunter succeeded his father, also named Duncan Hunter, who served 28 years in Congress.

“The name comes with a lot of baggage, but also with some strong advantages, such as every constituent Duncan Hunter, son and father, have helped in the past,” Kousser said. “A lot of this stuff was already out in 2018, and Hunter still won in a blue-wave year.”

John Wildermuth is a San Francisco Chronicle staff writer. Email: jwildermuth@sfchronicle.com Twitter: @jfwildermuth