Prime Minister David Cameron has said he would prefer to work with a European Union that "drives me crazy" than be a "quitter" and vote to leave.
Mr Cameron defended his record on the issues of migration and NHS spending - warning both would worsen with the economic impact of Brexit - as he discussed a range of topics during his first set-piece TV appearance of the referendum campaign.
Video report by ITV News Deputy Political Editor Chris Ship.
Speaking on Sky News's EU: In or Out programme, he insisted he would want Britain to join the EU if it wasn't a member before clarifying it would be on "British terms" to confirm he "would never have Britain join the Euro" - a requirement for new members.
Mr Cameron faced a boisterous audience and at times was accused of "scaremongering" and "waffling" as he made his case.
But he defended claims he and other leaders of the Remain bid had produced a fear-led campaign ahead of the June 23 public vote, insisting "this is not about scaring anybody".
The Prime Minister openly admitted his frustrations with the EU, saying: "I'm not sitting here for one minute saying this organisation is perfect."
He acknowledged that around 600,000 more EU nationals had come to live and work in the UK since the start of his premiership than Britons moving to the continent.
Mr Cameron said he stuck by his "ambition" of bringing net migration into the UK - which last month hit 333,000 - below 100,000.
But he insisted: "It would be madness to try to do that by trashing our economy and pulling out of the single market."
Mr Cameron gladly acknowledged the imperfect nature of the EU but said he wanted to remain at the negotiating table with fellow European leaders on the day German Chancellor Angela Merkel pitched for Britain to stay.
Mr Cameron was also challenged over immigration by retired NHS worker Alison Hyde-Chadwick, who demanded to know how the health service could be protected from "the seemingly never-ending stream of people from Europe".
He was accused of "waffling" by student Soraya Bouazzaoui, as he tried to assure her that Turkey would not be joining the EU "in decades".
Mr Cameron earlier faced laughter as Sky News political correspondent Faisal Islam ridiculed some of the claims made by the Remain camp, asking Mr Cameron: "What comes first, World War Three or the global Brexit recession?"
Mr Cameron insisted he had never claimed there would be a world war but added: "On our continent in the last century, twice we had an enormous bloodbath between our nations."
ITV News Political Editor Robert Peston suggested the TV appearance had neither helped nor hindered the pitch to sway voters.
Pro-Brexit former cabinet minster Iain Duncan Smith highlighted the significance of the PM refusing to set any date for meeting his commitment to cut net migration to below 100,000.
"I thought that was a telling moment because he realised it is difficult to achieve that without coming out of the EU and close our borders," said the former work and pensions secretary.
Ukip leader Nigel Farage criticised Mr Cameron, who he said "can't answer a single question".
Farage said the Prime Minister would do "anything to get away from immigration, anything to get away from the fact he can't control his borders and was he lying when he wrote the manifesto or is he lying now because somewhere this doesn't add up".
Justice Secretary Michael Gove will put the case for Britain to leave the EU on Sky News on Friday evening.