The General Election will go ahead as planned on June 8, despite the second terror attack to hit Britain during the campaign period, Prime Minister Theresa May has said.
Speaking in Downing Street after chairing a meeting of the Government's emergency Cobra committee, Mrs May confirmed that campaigning for the poll will resume on Monday.
National campaigning was suspended following the outrage by all major parties apart from Ukip, whose leader Paul Nuttall warned that stalling the democratic process could lead to more attacks.
The terror threat was not raised from its "severe" level at the Cobra meeting in response to Saturday night's outrage, which saw seven killed and 48 injured as terrorists drove a van into pedestrians at London Bridge and then attacked passers-by with knives.
But Mrs May made clear she intends to take action on a range of levels in response to the recent spate of atrocities, also including the car and knife murders of four people at Westminster in March and the killing of 22 by suicide bomb at the Manchester Arena last month.
She signalled action to clamp down on hate preaching and the use of the internet to spread Islamist ideology, as well as measures to end tolerance of extremism and a review of the powers of police and security agencies.
Jail sentences for extremism-linked crime – including less serious offences – could be lengthened, said the Prime Minister.
"It is time to say 'Enough is enough'," said Mrs May. "Everybody needs to go about their lives as they normally would. Our society should continue to function in accordance with our values.
"But when it comes to taking on extremism and terrorism, things need to change."
Mrs May said it was right for election campaigns to be suspended as a mark of respect to victims.
But she added: "Violence can never be allowed to disrupt the democratic process, so those campaigns will resume in full tomorrow and the General Election will go ahead as planned on Thursday.
"As a country, our response must be as it has always been when we have been confronted by violence. We must come together, we must pull together, and united we will take on and defeat our enemies."
The Union flag was flying at half mast over Downing Street as ministers and security chiefs gathered for the Cobra meeting, also attended by Home Secretary Amber Rudd, Foreign Secretary Boris Johnson, Defence Secretary Sir Michael Fallon, Health Secretary Jeremy Hunt, Transport Secretary Chris Grayling, Communities Secretary Sajid Javid and London Mayor Sadiq Khan, along with representatives of police and security and intelligence agencies.
Sunday's halt in campaigning is the second time that the election has been disrupted by terror atrocities, following a three-day pause after the Manchester attack.
The Joint Terrorism Analysis Centre (JTAC) moved the terror threat up to critical following the Manchester Arena attack, triggering heightened security measures including the deployment of military personnel to support police under Operation Temperer.
The threat level was last weekend lowered to the second highest category of severe, meaning an attack was judged "highly likely".
Political parties were quick to announce that they were putting their national campaigns on hold following the London Bridge attack.
Labour leader Jeremy Corbyn said: "The Labour Party will be suspending national campaigning until this evening, after consultations with other parties, as a mark of respect for those who have died and suffered injury."
And Liberal Democrat leader Tim Farron said: "The election must go ahead as planned. It is right that we suspend our national campaigning for a short while out of respect for those affected by these tragic events, but local campaigning can and must continue.
"The remainder of this campaign must be a collective showing of defiance and pride in our democratic values."
However, Mr Nuttall said: "The only guarantee that will come from our choosing to stall the democratic process again will be more attacks - it is what these cowards want us to do.
"For those of us seeking to serve the people of this country, it is our duty to drive the dialogue on how best to confront and defeat this brand of terrorism.
"That is what Ukip will be doing today and beyond. Therefore, I refuse to suspend campaigning because this is precisely what the extremists would want us to do."
Brexit Secretary David Davis said he did not believe there was any legal means of delaying the election from its scheduled date while Parliament was not sitting.
"I'm not sure it can be legally done," he told BBC interviewer Andrew Marr. "In order to do this, you'd have to have some change in the law and who's going to do that?
"Parliament no longer exists. I'm not a Member of Parliament for the duration, as are none of the other people who were MPs."
Mr Davis said it "may well be" that the attacks were intended to disrupt the election, adding: "In which case, all the more reason not to defer, not to deflect, to as far as possible within the bounds of propriety to not let this pull us off course."
Shadow foreign secretary Emily Thornberry said: "The response from London should be to be brave, be calm, carry on, but also do not let this derail our democracy.
"We go ahead with this election and we make sure people vote."
The Democratic Unionist Party's Ian Paisley Jr called for security to be stepped up at polling stations.
"People must feel safe especially at election time," said Mr Paisley. "Every effort must be made to protect polling stations across the kingdom.
"These terror attacks are attacks on our freedom and on our democracy designed to make us feel fear. Answer back with 'business as usual'. Madness to concede any ground to terror. Stand strong, democracy prevails."
Amid messages of sympathy and solidarity from many MPs, there were signs of the terror situation becoming part of the political debate.
Labour's John Mann renewed calls for internet companies to be made liable for the content which their sites host, after long-standing complaints that terrorists are able to use social media to communicate with one another.
Former Ukip leader Nigel Farage said: "We cannot suspend the campaign and normal life indefinitely. We want real action from our leaders, not more hand-wringing."
And ex-Labour MP Simon Danczuk, who is standing as an Independent in Rochdale, said: "Can't believe public will now vote Labour to put Corbyn in Downing Street when he opposes shoot-to-kill and is effectively terrorists' friend."
The attack came five days before the election, with opinion polls suggesting great uncertainty about the outcome of the contest.
One new opinion poll by Survation for the Mail on Sunday put Conservatives a single point ahead of Labour, on 40% to 39% for Mr Corbyn's party.
However, the findings contrast sharply with a ComRes poll for the Independent and Sunday Mirror which still shows the Conservatives with a 12-point advantage.
Opinium for The Observer also has the Tories ahead but with the gap narrowing to six points.
Ms Rudd said it was the right decision to suspend campaigning after the attack but insisted the election should go ahead as planned.
She told ITV's Peston on Sunday: "They are out to attack our values, our way of life, our democracy, our freedoms and it would be wrong to knock any of those in this period now and I think everybody I speak to is absolutely clear, they want the election to go ahead on Thursday."
Ms Rudd renewed calls for internet giants to tackle extremist material online and limit end-to-end encryption in the wake of the attack.
However she also pledged to "take the politics out of security" in the final days of the campaign, adding: "We will be very plain vanilla about making sure there is no political point-scoring as we go about trying to keep people safe."
A party source said that Mr Corbyn will give a speech in Carlisle on Sunday evening addressing the London attack and setting out his Labour's values.
The speech will be "statesmanlike" and in front of a small audience, the source said.
The party has cancelled a rally and its campaign battle bus will not be on the road during the course of Sunday.
Shadow foreign secretary Emily Thornberry criticised the Prime Minister for announcing a four-point plan to tackle terrorism, despite an agreement between the parties to suspend national campaigning.
She told BBC Radio 4's The World This Weekend: "I don't think it's right to get dragged into plans at this stage so soon after those attacks. I do think this is a matter of timing."
Asked if the announcement strayed into party politics, she said: "I think that it is drawing us into a debate. I think that there is time enough for us to discuss this issues.
"As I say, I don't think that anything she is proposing is anything that needs to be or will be dealt with tomorrow.
"I don't think there is any immediate steps she is putting forward and obviously if it was then that would be a different matter.
"To come out onto the steps of 10 Downing Street, immediately in the aftermath of a terrible outrage like this, was not something that would be expected.
"I just simply regret the approach that she has taken."