David Cameron has pleaded with older voters to back Britain staying in the European Union for the sake of their children and grandchildren.
In a surprise statement in Downing Street less than 48 hours before polls open in the referendum, the prime minister warned that voting Leave would be "irreversible".
And he made a last-ditch appeal to people who don't much like him or the Conservatives, saying he knew everyone wasn't "happy with what I've done".
The unexpected speech signalled the level of concern from Number 10 and the Remain camp ahead of the referendum, as opinion polls stay stubbornly close. Older voters are far more likely than younger people to vote Leave.
Speaking at a podium on Tuesday, Cameron said: "It will be future generations – the apprentices and the graduates starting out in life, the children learning in our schools, those yet to be born – they will be hit the hardest.
"And it's for that reason I want to speak very directly to those of my generation and older. I know Europe isn't perfect – believe me, I understand and I see those frustrations, I feel them myself."
The PM said that was why Britain had negotiated a "special status out of the euro" and had not signed up to "ever closer union" rules.
"We have the best of both worlds," he said. "So as you take this decision whether to remain or leave, do think about the hopes and dreams of your children and grandchildren.
"Remember: They can't undo the decision we take. If we vote out, that's it. It is irreversible. We will leave Europe for good. And the next generation will have to live with the consequences far longer than the rest of us."
He also made a personal plea to non-Conservative voters who were fed up with his leadership.
"The reason I came into politics was to help people to lead a better life – to get a good job, to earn a fair wage, have the chance to own a home to provide for your family and for your retirement," he said.
"That's why the thing I've focused on the most in the past six years in that building is sorting out the economy. Now I know I haven't got every decision right and I know everyone has not been happy with what I've done.
"But of this I am convinced. Indeed, of this, every living prime minister, whether Labour or Conservative, is convinced: Britain is better off inside the EU than out on our own."
Hours earlier, the Britain Stronger in Europe campaign posted a new video on Facebook featuring Yasmin, a Labour voter who is backing Remain but hates everything the Tories stand for. She shot to fame earlier this month when she told Cameron at BuzzFeed's town hall event: "You fucked every fucking thing up in this country."
In his statement, Cameron added: "Brits don't quit. We get involved, we take a lead, we make a difference, we get things done.
"If we left, our neighbours would go on meeting and making decisions that profoundly affect us, affect our country, affect our jobs, but we wouldn't be there. They would be making decisions about us but without us."
Steve Hilton, the PM's former policy guru, who is supporting Leave, told BBC News the speech was "weird" and that there was "nothing new" in it.
"What you just saw from the prime minister was an admission that they have lost the economic argument, they have lost the argument on immigration and so he has been wheeled out by rather panicky spin doctors, it seems to me, to try and change the subject."