MANCHESTER (NYTIMES) - Just when Prime Minister Theresa May of Britain needed a rousing, commanding speech to restore authority over her warring Conservative Party, she endured a nightmare.

First there was the prankster, theatrically handing her a notice that she was fired. Then a persistent cough turned her delivery into a croak that was painful to the ear.

Then there was the falling F.

The letters on the slogan behind her, "Building a Country That Works for Everyone," lost the F, turning "for" into "or."

Ending a four-day party conference on Wednesday (Oct 4) dominated by speculation about her fragile leadership, May struggled through her address, with the audience periodically giving her protracted applause to allow her time to rest her voice.

She repeatedly drank from a glass of water. The chancellor of the Exchequer, Philip Hammond, handed her a cough lozenge. Sometimes she seemed almost reduced to a faltering whisper.

The speech highlighted the problems confronting May. Her battle to complete it seemed to some like a metaphor, the set of mishaps overshadowing the messages she hoped would dominate the news.

The Conservative Party conference in Manchester was the first since May gambled by calling a general election in June, a political blunder that cost her party its majority. An unexpectedly strong performance from the opposition Labour Party destroyed much of her authority in the process.

Under the left-wing leadership of Jeremy Corbyn, Labour's anti-austerity message struck a chord, particularly with younger voters, who turned out in greater numbers than usual, leaving many Conservative activists in Manchester wondering how to compete.

As the debate about the Conservative Party's future has unfolded at the conference centre and beyond, May's potential successors have exploited a chance to grab the limelight.

None took that opportunity more ruthlessly than the foreign secretary, Boris Johnson, who has made two interventions undermining May's strategy for negotiating Britain's withdrawal from the European Union, known as Brexit.

Johnson created a contretemps as well, telling a conference panel that the Libyan coastal city of Sirte, a former redoubt of the Islamic State terrorist group, could be "the next Dubai" if the authorities "could just clear the dead bodies away." Critics, including some members of the party, said he should resign.

While there seems to be no immediate plot to unseat May, analysts say that the longest she can expect to remain in her job is until March 2019, when the withdrawal is to take place. The party conference, and this speech in particular, was an opportunity to reassert her authority over a Cabinet squabbling over the details of Brexit.

That was not how it turned out.

"Before the speech, most people would have bet on her coming out of the conference season alive, although the sharks were already circling," said Tim Bale, professor of politics at Queen Mary, University of London, referring to potential rivals for May's job.

"The speech has put blood in the water," he said.

On Wednesday, May promised that more affordable homes would be built to address the country's housing crisis. She detailed a cap on energy prices and promised to create a British version of the American dream.

She also apologised to Conservative Party members for having led an election campaign that was "too scripted, too presidential," and spoke only briefly about the divisive issue of Brexit.

But May was soon interrupted by a prankster from the audience who handed her a P45 - a form sent to Britons as they leave a job - saying "Boris asked me to give you this." Guards ejected him from the hall.

Though the episode raised some security questions, the police later said that the man, Simon Brodkin, a comedian, had accreditation to attend the conference. That was despite the fact Brodkin performs as a character called Lee Nelson, whose website mentions pranks including disrupting a news conference by throwing bank notes at Sepp Blatter, the former president of FIFA, the governing body of international soccer.

May's colleagues put their best gloss on events, arguing that her performance had illustrated her determination, and that voters would understand and sympathize with her predicament.

Jeremy Hunt, the health secretary, described it as the "ultimate tough gig," but said that "she battled on," and that "what the public will take away from that, curiously, is that sense of duty."

Nevertheless, others expected frustration among May's allies that a speech that had been going well until the interruption spiraled out of control, overshadowing announcements that had sought to wrest attention from Corbyn's agenda.

The biggest of those was the pledge to place limits on energy prices - though there was no detail on how many people it would affect. Some critics complained that the idea conflicted with May's broader defense of the free-market economy, which the Conservatives say is threatened by Corbyn.

For May's supporters who watch clips of the speech on television news, her throaty delivery may not be as grating as it was for the audience who heard its entirety.

Certainly, there was support from activists outside the hall, including one party member, Joe Porter, who said May's determination to finish her speech illustrated her "professionalism," adding, "We are all human beings, we all get coughs."

Another party member, Enoch Manto Lieu, said that the episode might help humanize May, who has been mocked by critics as "Maybot," a reference to her robotic, scripted answers to questions.

For her part, May sought to show some self-deprecating humor by posting a photo of throat medication on Twitter.

There was empathy from some fellow politicians, including Nicola Sturgeon, Scotland's first minister, whose Scottish National Party holds its conference beginning Sunday.