Prime Minister David Cameron has urged voters to opt for a "tolerant, liberal Britain" and reject a British EU exit, or Brexit, in Thursday's referendum.
"If you don't know, don't go," Cameron told undecided voters on Sunday, in his first major intervention in the campaigning since the murder of Labour politician Jo Cox, who, like Cameron, had urged the public to vote Remain.
"Jo embodied Britain at her best – a country that is decent and compassionate; one that reaches out to make the world a better place," Cameron wrote in The Sunday Telegraph.
"I'm so proud of Britain – this open, tolerant, big-hearted country of ours," he said. "But I believe this referendum has now become a watershed moment for our country."
"And we are going to have to make a defining decision on Thursday: are we going to choose Nigel Farage's vision – one which takes Britain backwards; divides rather than unites; and questions the motives of anyone who takes a different view," Cameron asked, referring to the leader of the anti-EU UK Independence Party.
"Or will we, instead, choose the tolerant, liberal Britain; a country that doesn't blame its problems on other groups of people; one that doesn't pine for the past, but looks to the future with hope, optimism and confidence?"
An unemployed man who sympathized with racist and right-wing extremist groups, and had a history of mental illness, was charged with murdering Cox.
Cameron and Labour leader Jeremy Corbyn, who also backs Remain, appeared together on Friday at a vigil for Cox.