The Manchester bombing has thrust terrorism to center stage ahead of Britain’s hotly contested June elections, as British Prime Minister Theresa May on Saturday warned that “the country should remain vigilant” even as authorities say concerns about a new attack have eased.

May lowered Britain’s security threat back where it was before the Monday suicide bombing at a pop concert killed 22 people. But even though authorities appeared satisfied that they had captured most of the people they suspect to have taken part in the attack, security fears continued to reverberate through the political campaign ahead of the June 8 election.

“A significant amount of police activity has taken place in the last 24 hours,” May said Saturday after a meeting of her top security advisers.

Police, meanwhile, arrested two additional suspects early Saturday in Manchester, bringing the number of people in custody to 11.

[British authorities believe most involved in Manchester bombing are in custody]

(Sarah Parnass/The Washington Post)

“We are getting a greater understanding of the preparation of the bomb,” said Mark Rowley, the top counterterrorism official at Britain’s Metropolitan Police.

The announcement came a day after May and her Labour opponent traded vicious barbs about the role British involvement in Middle Eastern conflicts has played in provoking terrorist attacks. Before Monday’s bombing, the election had appeared firmly in the grasp of May’s Conservatives.

May called the election seeking the public’s stamp of approval for the government’s strategy to negotiate Britain’s break from the European Union.

That was suddenly on the sidelines.

“The war on terror is not working,” Labour leader Jeremy Corbyn said Friday, as campaigning resumed after a three-day break following the attack. Organizers preceded Corbyn’s speech with a minute’s silence to honor the 22 people who died in the bomb blast.

In the address, Corbyn linked Britain’s foreign wars to terrorist attacks but stressed the connection “in no way reduces the guilt of those who attack our children.

“Many experts, including professionals in our intelligence and security services, have pointed to the connections between wars our government has supported or fought in other countries and terrorism here at home,” he said.

Corbyn, a longtime critic of the Britain’s wars in Iraq and Afghanistan, also pledged that if he were prime minister, troops would be deployed abroad only if there was a clear need, proper resources and a plan for “lasting peace.”

His opponents wasted no time in accusing him of trying to politicize the attack.

'I have been here at the G-7 working with other international leaders to fight terrorism,” May said Friday after a summit meeting with top European leaders and President Trump. “At the same time, Jeremy Corbyn has said that terrorist attacks are our own fault.

“There can be no excuse for terrorism,” she said.

Boris Johnson, Britain’s foreign secretary, said that Corbyn’s position was “absolutely monstrous.”

[Libya becomes a key focus of the Manchester bombing probe]

Liberal Democrat leader Tim Farron said that Corbyn was trying to score a “political point” and that he disagreed with his timing.

Corbyn responded to the criticisms in a late-night BBC interview, saying that he wasn’t defending the “indefensible” Manchester attack but was reflecting the view that countries that want a secure future need to reflect on foreign policy.

“Any sensible government has to look at what is happening in Libya, a huge ungoverned space and apparently a source of some awful extremism,” he said. The 22-year-old attacker, Salman Abedi, was born in Manchester to Libyan parents and had traveled to Libya ahead of the bombing.

Still, some of the damage had already been done, with Britain’s powerful right-wing tabloids ripping into the Labour leader.

“This is a man who, for years, has been one of Westminster’s foremost apologists for terrorism,” wrote Guy Adams, a columnist in the Daily Mail.

But while the Conservatives lashed out at Corbyn's remarks, they could also galvanize his base.

Corbyn’s speech “will outrage many Conservatives, but if his aim is to mobilize his core left liberal vote, then it could work,” said Tim Bale, a politics professor at Queen Mary University of London. “Now, how that will play with the majority of voters is another matter.”

Recent polls have shown the Conservatives’ lead significantly narrowing.

When May called the snap election last month, her opponents were weak and fractious. One pollster gave her Conservative Party a towering 23-point lead. But a new YouGov poll on Friday showed the Conservative Party’s lead has slipped to five points — a dramatic shift that would put Labour on track to actually gain seats, something few political commentators expected weeks ago.

Many attribute the shift to Labour’s successful manifesto launch and a controversy in the Conservative Party over its plans — since abandoned — to cut social benefits for the elderly.

It’s possible, analysts say, that the Conservatives could inch back up in the polls following the terrorist attack as the narrative shifts away from their recent difficulties to focus on May’s leadership and security issues.

Before becoming prime minister, May served for six years as Britain’s home secretary, the country’s top domestic security official. She is also seen as the leader most likely to keep Britain safe from terrorist threats.

“May’s recent difficulties will now be overtaken by events,” wrote Mujtaba Rahman, an analyst with the Eurasia Group, in a briefing note. He said that the election campaign will shift to a “stronger focus on leadership, where Labour is at a strong disadvantage with Jeremy Corbyn in charge.”

Bale agreed that conventional wisdom suggests that May could benefit but also warned that it could backfire if it is proven that there were failings in the security services.

“Normally, there is a degree of rallying around an incumbent or president or prime minister in this situation. But there are downside risks as well if investigation proves the security system could have spotted this man earlier and can pin that on lack of resources,” said Bale.

But whatever way the pendulum swings, he said, “it’s difficult to believe the election campaign will be the same as it might have been before the bomb went off.”

Read more

Trump calls for investigation of U.S. leaks in Manchester bombing probe

Two bombings in Manchester, 21 years apart, show the changing nature of terrorism

Why Britain’s government doesn’t leak the way America’s does

Today’s coverage from Post correspondents around the world

Like Washington Post World on Facebook and stay updated on foreign news