Ukip leader Nigel Farage has accused David Cameron and the Remain campaign of a "despicable" attempt to create a link between the EU referendum and the death of Jo Cox to improve their chances of winning Thursday's referendum.
Mr Farage said Remain were "scared witless" about the prospect of defeat on June 23 and were trying to "conflate" the motivations of the Labour MP's alleged killer with those of the millions of voters who want to leave the European Union.
The Ukip leader also dismissed the defection to the Remain camp of former Conservative chair Baroness Sayeeda Warsi as a "Number 10 put-up job".
Lady Warsi - who was the first Muslim woman to attend Cabinet but quit the Government in 2014 over the Gaza conflict - said her decision to change sides was sparked by a "xenophobic" poster released by Mr Farage, as well as "lies" from Michael Gove over the prospect of Turkey joining the EU.
But her defection was greeted with bemusement by Leave campaigners, who said they were not aware that she had ever been a Brexit supporter.
Meanwhile, leading Leave campaigner Boris Johnson issued an appeal for voters to "change history", writing in the Daily Telegraph: "Now is the time to believe in ourselves, and in what Britain can do, and to remember that we always do best when we believe in ourselves.
“This chance will not come again in our lifetimes, and I pray we do not miss it. You can change the whole course of European history - and if you vote Leave, I believe that change will be overwhelmingly positive.”
Speaking as MPs gathered in Westminster for a recall of Parliament to pay their respects to Mrs Cox, Mr Farage accused the Remain camp of trying to use her death for political advantage.
Mr Cameron has faced criticism from some quarters for retweeting a link to the last article written by the Batley & Spen MP, in which she argued that Britain could deal with the issue of immigration more effectively by remaining in the EU.
The Ukip leader - who acknowledged on Sunday that Mrs Cox’s death had taken momentum out of the Leave campaign - told LBC radio: “I think there are Remain camp supporters out there who are using this to try to give the impression that this isolated horrific incident is somehow linked to arguments that have been made by myself or Michael Gove or anybody else in this campaign, and frankly that is wrong.”
He insisted that he had said nothing “inciteful” during the campaign, adding: “What we are seeing here is the prime minister and the Remain campaign trying to conflate the actions of one crazed individual with the motives of half of Britain who think we should get back control of our borders and do it sensibly ...
“We have a prime minister and a chancellor and other big political leaders in Britain who are scared witless. They thought they would win this referendum by a country mile.
“They know it’s neck and neck, they know it’s down to who turns out on the day to vote, and there is no level of denigration or false association that they will not stoop to, but I think people are intelligent enough to see through this sort of thing.”
Mr Farage defended the controversial poster released hours before Mrs Cox’s death, which showed a column of migrants walking through the European countryside under the slogan “Breaking Point”.
Lady Warsi described the poster as "indefensible", telling BBC Radio 4's Today programme: "This kind of nudge-nudge, wink-wink xenophobic racist campaign may be politically savvy or politically useful in the short term, but it causes long-term damage to communities.
“The vision that me and other Brexiters who have been involved right from the outset, who had a positive outward-looking vision of what a Brexit vote might mean, unfortunately those voices have now been stifled and what we see is the divisive campaign which has resulted in people like me and others who are deeply Eurosceptic and want to see a reformed relationship feel that they now have to leave Leave.”
Challenged over the poster, Mr Farage said: “If the timing of her murder and me putting out that poster has upset people, I’m sorry. That certainly wasn’t the intention. The intention was to use that poster for a day to point out that the EU is a failed project in every sense.”
But he described Lady Warsi’s defection as “the biggest put-up job I’ve ever seen”, saying she “never supported Britain leaving in the first place” and had refused to appear on campaign platforms.
Senior Leave supporter and Conservative MEP Daniel Hannan questioned whether the Tory peer had been part of the Brexit campaign, saying: “When I invited Sayeeda Warsi to join the Leave campaign, she declined. Fair enough, obviously. But how is this a ‘defection’?”
And prominent Brexiteer Toby Young asked: "Was Warsi on our side? Who knew?"
But Lady Warsi said she had spoken for Brexit within the last five weeks and promoted Leave in the media four weeks ago.
“I’ve been making the case for leave long before Vote Leave had even formally been established,” she said.
Agencies