Gregorio Borgia, Associated Press
FILE - In this Oct. 28, 2014 file photo, an employee counts British pounds and Euro notes at a currency exchange office in downtown Rome. As Britain prepares to vote whether to leave or stay in the European Union, goodwill between the continent and the island nation is fraying on both sides.

LONDON — The pound and global stock markets surged Monday as both opinion polls and betting markets suggested an increase in support for Britain to remain in the European Union in the final crunch week of the vote.

The death of a pro-Europe lawmaker in a gun and knife attack last week may have sapped some of the momentum of campaigners fighting to leave the 28-nation bloc in Thursday's vote. Nigel Farage, a leading figure in the "leave" camp, accused his opponents of trying to capitalize on Jo Cox's slaying for political advantage.

Backers of "leave" on Monday also lost the support of a former Conservative Party chair, who switched sides after expressing disgust for a poster depicting a crowd of migrants walking through Europe with a warning in capital letters that said: BREAKING POINT. Sayeeda Warsi said Monday that moderate voices in the "leave" campaign have been drowned out in favor of campaign of xenophobia and hate.

"The pause in the campaign seems to have lent crucial support to team 'remain,' with only four days to go until the vote," said Kathleen Brooks, research director at Gain Capital. "The markets have always been more comfortable with the U.K. remaining in the European Union."

The pound rose 1.8 percent to $1.4619 Monday, rebounding from last week, when it hit its lowest levels since April. In stock markets, the FTSE 100 was up 2.6 percent and other indexes around the world were just a buoyant, with Germany's DAX 3.1 percent higher.

Opinion polls are now back to even, though the shifts are very small from earlier polls last week leaning to exit

But the shift in opinion was small, and it was unclear precisely what was behind the shift, said respected pollster Ben Page of Ipsos MORI. That said, three out of four polls taken since Cox's death show a shift to remain.

"The two sides are at a level pegging. It's all in the margin of error," Page said. "It could be anxiety about the economy. It could be revulsion about her murder."

More clear were the betting markets, which have consistently favored remain. Betting market Betfair said the probability of "remain" has risen to 72 percent, from Friday's 65 percent.

However, the shifts also suggest that turnover will be critical in the vote, as supporters of "leave" are seen as being more committed than those of "remain." The weather is also seen as being a factor, as Britain has been drenched in unsettled weather for days.

"If the weather continues as it is today, it will be very close indeed," Page said.

The "leave" campaign came out swinging Monday, accusing "remain" of linking the actions of the lawmaker's accused killer with the beliefs of many who simply want to leave the 28-nation bloc.

"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 ... in this campaign, and, frankly, that is wrong," Farage told LBC radio. "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,"

Farage defended the immigration poster with a column of immigrants that was released only hours before Cox's death. The poster infuriated Warsi, one of the most prominent Muslim politicians in the country.

"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," Warsi said.

Campaigners for "leave" were bemused by her decision, saying they weren't even aware she had been a supporter.