Boris Johnson, the prominent British politician who is among frontrunners in the race to become the nation's next prime minister, is reportedly appealing against a summons that requires him to appear in court to answer claims he committed misconduct in public office.

Johnson, who served as the United Kingdom's foreign secretary before he resigned in July,has reportedly instructed his lawyers to argue that the summons issued by District Judge Margot Coleman on May 29 was unlawful and that criminal proceedings should be suspended.

Campaigner Marcus Ball brought the private prosecution over Johnson's alleged claims, made during campaigning ahead of the 2016 referendum on whether the UK should leave the European Union, that the UK sent the EU 350 million pounds ($443 million) a week. Ball alleges the figure was deliberately exaggerated in order to trick voters into choosing to leave the EU in the in/out referendum.

Johnson has been a prominent supporter of the UK exiting the EU and was a fierce critic of May as she negotiated divorce terms with the bloc and while she attempted to persuade the British Parliament to support the deal she had agreed with Brussels.

Having helped persuade May to resign from office, he is now seeking to replace her as prime minister and leader of the ruling Conservative Party.

The Guardian newspaper reported that Ball said Johnson had launched a judicial review application in administrative court with the aim of derailing the private prosecution.

If Johnson's lawyers are successful in their request for a judicial review, a senior judge will determine whether the summons issued by Coleman was lawful and whether the trial should be allowed to proceed as planned.

Ball launched his private prosecution after a crowdfunding campaign raised more than 200,000 pounds.

He told the Reuters news agency that fighting Johnson's judicial review application would be a "particularly expensive part of the legal process" but he said it was important to try to hold politicians to account.

"When politicians lie, democracy dies," he said.

Johnson has not yet commented on the situation.

May is set to formally resign as prime minister on Friday and Johnson is among 12 hopefuls who have thrown their hats in the ring and who are still in the race to replace her.

While Johnson is seen as a bookmakers' favorite, especially after he was endorsed by visiting United States President Donald Trump on the weekend, he is joined in the leadership race by several other big-hitters, including Michael Gove, the UK's education secretary, Rory Stewart, the international development minister, Matt Hancock, the health secretary, and Home Secretary Sajid Javid.

May has said she will stay on as caretaker prime minister until her replacement is found, a process that political pundits anticipate will probably conclude by the end of July.