Theresa May had to battle losing her voice and being interrupted on stage by a comedian as she sought to reassert her Conservative leadership.
Mrs May, who at one point was handed a throat sweet by the chancellor, did make it to the end of a speech in which she vowed to "renew the British dream".
She announced plans for more council houses and a cap on energy prices.
But they were overshadowed by the problems she had delivering the set-piece speech in Manchester.
BBC political editor Laura Kuenssberg said the annual conference "was meant to be about restoring Theresa May's authority - it may prove instead to have been further undermined".
Mrs May was interrupted early on in her speech by comedian Simon Brodkin - also known as Lee Nelson - who managed to make it to the podium to hand her a P45, a redundancy notice, saying to her that "Boris asked me to give you this".
After he was removed and she got encouraging cheers from the audience she joked that the only P45 she wanted to give out was to Jeremy Corbyn.
But she struggled to finish the speech because of a croaky voice, having to stop several times to drink water.
Sources close to the prime minister have said that the PM had caught the "conference cold", and that her many interviews and meetings this week have taken their toll on her voice.
They say the prankster who interrupted her speech has been arrested for a breach of the peace and there will be a thorough investigation of security.