Boris Johnson's plan to suspend Parliament is facing legal challenges in London, Edinburgh and Belfast, as the move gathers traction and divides opinion.
MPs have denounced the move as anti-democratic, while an Irish minister compared Mr Johnson to Oliver Cromwell and an author said he thinks of a rope and lamp-post when he hears the prime minister's name.
On the other hand Cabinet ministers went on the offensive trying to convince opponents that the move was following precedent.
Leader of the House of Commons Jacob Rees-Mogg described the outrage at the suspension of Parliament as “phoney”.
The leading Brexiteer and Johnson ally also hit back at Commons Speaker John Bercow’s intervention on the decision to prorogue Parliament, saying it was “not constitutional” for him to speak out in such a way.
Mr Rees-Mogg insisted the move to prorogue Parliament for almost five weeks was not undemocratic and "fully in line with the constitution".
Meanwhile Labour leader Jeremy Corbyn said opposition MPs will start their attempts to block a no-deal Brexit on the first day back after the parliamentary summer recess.
Mr Corbyn said: "We will be back in Parliament on Tuesday to challenge Boris Johnson on what I think is a smash-and-grab raid against our democracy where he's trying to suspend Parliament in order to prevent a serious discussion and a serious debate to prevent a no-deal Brexit."
And the EU's chief Brexit negotiator made it clear he was not ready to retreat on the issue of the Northern Ireland backstop, despite pressure from the Prime Minister.
Mr Barnier tweeted: "PM @BorisJohnson has said that the UK will leave the EU on 31 Oct. In all circumstances, the EU will continue to protect the interests of its citizens and companies, as well as the conditions for peace and stability on the island of Ireland. It is our duty & our responsibility."
His comments came after the resignation of Scottish Tories leader Ruth Davidson, who demanded the PM strike a deal with the EU as she quit.
And, Lord Young, the government whip in the Lords, also quit, saying: “I am very unhappy at the timing and length of the prorogation", adding that it risks "undermining the fundamental role of Parliament”.
Amid the furore, MP for Watford Richard Harrington signalled he would resign, but did not cite Brexit or prorogation.
The former minister said: "In a statement explaining his decision to stand down, Mr Harrington said: "Having had the privilege of serving as MP for Watford for almost 10 years, I have decided to retire from frontline politics."It had always been my intention to step down at the next general election, due under the Fixed Term Parliament Act in 2022.
"However, with the current increasing uncertainty about an earlier election, I believe it right for me to make clear my intentions now.
"Therefore I have told my constituency chairman that I will not be offering myself for selection as the Conservative Party candidate for the next general election, whenever that may be."
Meanwhile, legal bids to challenge the prorogation were launched at the High Courts in London and Belfast, and Scotland's highest civil court.
A cross-party group of around 70 MPs and peers are backing the action at the Court of Session in Edinburgh.
An urgent application for a judicial review has also been made at the High Court in London by campaigner Gina Miller, who previously won a landmark ruling that MPs would have to vote before the Government could invoke Article 50 to formally start the UK's exit process from the EU.
A judiciary spokeswoman said: "The defendant is the Prime Minister. The application is being considered."
The legal bid in Belfast to injunct Boris Johnson's move was adjourned for 24 hours after being launched by prominent victims campaigner Raymond McCord, who was also already pursing legal proceedings against the potential proroguing of Parliament.
Watch ITV News podcast Acting Prime Minister presented by Paul Brand and featuring key Brexiter Mark Francois:
The prime minister's move, which takes effect from around September 10, sparked a series of protests up and down the country and brought a storm of noise from Opposition leaders.
Author Sir Philip Pullman denied he was advocating the hanging of Boris Johnson after posting a since-deleted tweet which said he thinks of a rope and lamp-post when he hears the prime minister's name.
In a series of tweets on Friday, the author said: "I've deleted a tweet which apparently upset a lot of people. I don't advocate hanging Boris Johnson. I think that would be a very bad idea.
"Recent events have aroused my anger to the point where I temporarily lost my judgement. In the heat of the moment I made a tactical error.
"Johnson's attempt to silence Parliament is a low point in our nation's political history. It was not my aim to distract from the genuine and legitimate outrage of many people at this, and I'm sorry it happened."
And in a tweet, which he later deleted, Minister of State Michael D'Arcy said the PM's decision to suspend Parliament was "perhaps the most anti-democratic decision since the Protectorate government, which Oliver Cromwell set up, was established".
But Mr Rees-Mogg said: “I think the outrage is phoney and it is created by people who don’t want us to leave the European Union and are trying very hard to overturn the referendum result and don’t want the benefits of leaving the European Union.”
He added: “Parliament wasn’t going to be sitting for most of this time anyway. This is completely constitutional and proper.”
Work and Pensions Secretary Amber Rudd remained tight-lipped on her views of the decision to suspend Parliament on a visit to Belfast.
Earlier in the summer, she described the suggestion of proroguing Parliament to push through a no-deal Brexit as "absolutely outrageous", "extraordinary" and "ridiculous".
But she dodged repeated pressing on the issue insisting she was focused on her role.
Tory grandee Ken Clarke - who has set his stall out to block a no-deal Brexit - again said he would be willing to work with Labour leader Jeremy Corbyn and to do “anything necessary to avoid the country making the childish mistake of crashing out with no deal”.
Labour and opposition parties vowed to press ahead with attempts to block a no-deal Brexit using legislation despite the decision to suspend Parliament for more than a month before the October 31 exit deadline.
Thousands of people rallied for hours outside Parliament on Wednesday night, and there were smaller demonstrations in other towns and cities as Remainers reacted to the prorogation announcement.
Around 1.5 million people have also signed a petition calling on Mr Johnson not to suspend Parliament.