After Nigel Farage's exit, what's the future of Britain's Independence Party?

Nigel Farage officially stepped down on Friday as leader of Britain’s UK Independence Party (UKIP), handing over the reins to European Parliament member Diane James and inaugurating a new era of uncertainty for a party that rose to become the standard-bearer of Britain's anti-globalist right.

"I literally couldn't have worked any harder, or couldn't have been more determined," Mr. Farage told UKIP party members at a conference on Friday, according to the BBC. "It's been my life's work to get to this point. I think, folks, I've done my bit." 

On the campaign to leave the European Union, he added, Britain had "won the war."

"Now we have to win the peace," he said, warning of signs that British prime minister Theresa May might be softening on immigration controls and other issues that drove pro-Brexit feeling, and urging advocates not to relent until negotiations drew to an official close.

The departure of Farage, a charismatic figure whose repeated returns from retirement were thought to be compelled by a lack of steady leaders to fill the vacuum, throws into doubt the party's future, at a moment when European leaders are expressing concerns that the bloc might be moving toward disintegration.

"I think the key to UKIP's success lies, frankly, in what happens in the negotiations," says David Parker, a political scientist at Montana State University who has been studying the British political system. If negotiations over Britain’s exit drag on and the party’s demands aren't met, he adds, they might stay in power.

"If immigration numbers are addressed, I think UKIP will struggle to find itself over the next few years," he tells The Christian Science Monitor.

"For third parties, this is their Achilles heel. They pop up, have success, and when they move the agenda" of big, rival parties closer to their own, their influence tends to wane, Dr. Parker says. "Big major parties tend to co-opt issues from those parties."

Diane James, who came close to winning a parliamentary seat in the southern constituency of Eastleigh in 2013, isn't seen as an inspiring candidate in the northern England towns where UKIP may try to pick up votes among traditional Labour Party supporters, The Guardian reports. However, she won 47 percent of party members' votes, more than any competitor. One of her main priorities will likely be the "professionalization" of a party known for running candidates whom many voters consider eccentric, to the point of unseriousness.

"Professionalism though will be top of my agenda," she said in a Friday speech accepting her election as party leader, according to The Guardian. "If we are going to reach and achieve the goals this party is still capable of achieving, then change is going to have to happen."

Part of the difficulty of the transition to a post-Farage era is the intense loyalty he encouraged.

"Behind the scenes, Farage also recruited an intensely loyal group of young activists, whose sole job was to follow his command and attack his critics," wrote Matthew Goodwin, a professor of politics at the University of Kent and co-author of a book on UKIP's ascendancy, in an August column in the New European, a "pop-up" publication aimed at British voters who favored remaining in the EU. Those activists, he added, "played a central part in ensuring that Farage's ordered were executed."

"For much of the past two years, they have been continually at Farage's side on the campaign trail, from events in the morning, through to late-night curries and pints in the pub," Dr. Goodwin wrote. 

Another unknown for the party's continued influence has sprung up in The People's Movement, a pro-Brexit group led by Arron Banks, an important UKIP donor. The group will seek reform of Britain's political system that includes the dissolution of the House of Lords, to be replaced with an elected body, and the elimination of about half of the country's parliamentary seats, as the Financial Times notes. But it's unclear whether the new group's money and energies will complement those of UKIP, or eat away at its resources and support.

The election of Ms. James came the same day as European leaders tried to drum up public faith in the EU at a summit in Bratislava, Slovakia.

"Everyone is aware of the situation," said French president Francois Hollande, according to the ABC. "Britain has decided to leave and there are questions about the future of Europe"

"Either we move in the direction of disintegration, of dilution, or we work together to inject new momentum, we relaunch the European project."