According to an ORB poll cited in a Reuters report, May's Conservative Party holds the lead with 44 percent while the Labor Party comes second with 38 percent, and Liberal Democrats in a distant third position with seven percent followed by the far-right UK Independence Party favored by only four percent of those polled on May 24-25, after the Manchester terror incident.
The Conservatives were on 45 percent, down one percentage point since Opinium's last survey, and Labour were on 35 percent.
Yesterday Britain's terror threat was reduced from critical to severe as Theresa May told Britons to "remain vigilant".
On who will keep the United Kingdom safe from terrorism, voters back Theresa May over Mr Corbyn by a huge 42%-16% margin, while she has a 26-point lead (42%-16%) over who is the best leader to oversee Brexit negotiations.
ComRes said voters are still more likely to say that May best fits the majority of the measures tested but her ratings have fallen, while Corbyn's have risen, on nearly every measure tracked.
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The Prime Minister was seen as best choice to represent Britain on the world stage, lead negotiations on Brexit and reduce net migration, while Corbyn was rated best to improve the NHS, look after the interests of hard-working families and protect older people.
The pound weakened after the YouGov poll was published. If the swing to Labour were uniform across the country, Nrs May would lose seats in the House of Commons, with the Tory majority falling to two from 17, The Times said. Much of the national political debate has been about security and how to stop terror attacks but today Labour has tried to move the agenda onto football.
Corbyn said the sight of the army on Britain's streets after the attack is a clear sign that the UK's foreign policy and approach to fighting terrorism is not working, reported the Guardian. "Now is the time to focus on our British values, our intolerance of terrorism and stand united".
"I think we have to distinguish between conducting private meetings and supporting violent attacks and actually being on a platform", said the shadow home secretary. "Northern Ireland shows us that the way forward is not just about the military, it's about engaging communities", she said.
As well as promising an extra 10,000 police officers, Jeremy Corbyn says he will recruit an extra 1,000 security and intelligence agency staff.
He said: "The bombing campaign was completely wrong because it was taking civilian lives".