The shortest-serving prime minister in the history of Great Britain, Liz Truss, will this week attempt a political comeback, rallying behind libertarian and right-of-center Tory MPs as she seeks to boost the profile of a new “Popular Conservatism” movement challenging the current prime minister, Rishi Sunak.

Ms. Truss, whose tenure as prime minister in the fall of 2022 lasted just 50 days, will reportedly head up a conference of these so-called “PopCons” during a conference in central London Tuesday. Also attending the conference, according to the Times of London, will be Brexit champion Nigel Farage and a former business secretary, Sir Jacob Rees-Mogg.

The group will be headed by Mark Littlewood, who is credited with drawing up the libertarian economic policies that led to the popular backlash against her in 2022. It will focus on advancing more conservative takes on such issues as immigration and tax cuts in the next Tory party manifesto ahead of a general election that must be held no later than late January 2025.

People behind the Popular Conservatives push say it promises a “new movement aiming to restore democratic accountability to Britain” and deliver “popular” Tory policies.

Mr. Farage’s attendance at the event is sure to anger more moderate factions within the Conservative party who have rallied around Mr. Sunak in recent weeks despite polls that suggest his popularity has plummeted in recent months.

Nearly three-fourths of Britons have told pollsters that they have an unfavorable opinion of the prime minister. Those same polls suggest that Mr. Sunak is less popular now than Ms. Truss was when she was forced out of office.

After failing to win any seats in the 2019 general election with his Brexit Party, Mr. Farage embarked on a career as a television pundit in both the United States and the United Kingdom. He fronted several rallies for President Trump during the 2020 campaign and appears regularly on Fox News in the United States and a conservative broadcaster in Great Britain, GB News.

Mr. Farage is reportedly set to return to public life in the United Kingdom under a rebranded Reform UK party to challenge Mr. Sunak’s Tories in the upcoming election. Mr. Farage tells the Sunday Telegraph that he will be attending Tuesday’s conference in his role as a presenter for GB News, but his presence at the meeting is sure to fuel speculation about a political revival that could splinter a Tory party already divided over the immigration issue and other populist policies.