The prime minister’s decision to suspend Parliament has prompted an angry backlash from MPs and opponents of a no-deal Brexit.
It sparked protests across the country, a legal challenge and a petition with more than a million signatures.
The government said the five-week suspension in September and October will still allow time to debate Brexit.
Leader of the House Jacob Rees-Mogg said opponents of the PM were “phoney” and just wanted to stay in the EU.
He told BBC Breakfast that Parliament would normally head into a recess for the party conferences in September anyway – adding there would still be time to debate Brexit in the Commons before the scheduled departure date of 31 October.
However, House of Commons Speaker John Bercow – who does not traditionally comment on political announcements – described it as a “constitutional outrage”.
Former Tory Chancellor Philip Hammond called it “profoundly undemocratic”.
The leader of the Liberal Democrats, Jo Swinson, told BBC Newsnight that the prime minister “is prepared to deny people their voice through their representatives in Parliament to force through a no-deal Brexit”.
Scotland’s First Minister Nicola Sturgeon said MPs must come together to stop the plan next week, or “today will go down in history as a dark one indeed for UK democracy”.
Meanwhile, Cabinet minister Michael Gove added the suspension, which was approved by the Queen on Wednesday, was “certainly not” a political move to obstruct opposition to the UK leaving the EU without a deal.
But Ruth Fox – director of parliamentary experts the Hansard Society – said this prorogation was “significantly longer than we would normally have” for the purpose of starting a new parliamentary session.
Ms Fox told BBC Radio 4’s Today programme that, depending on the day the suspension began – and on whether MPs would have voted to have a party conference recess at all – the prorogation could “potentially halve” the number of days MPs have to scrutinise the government’s Brexit position.
On Wednesday, Mr Johnson said a Queen’s Speech would take place after the suspension, on 14 October, to outline his “very exciting agenda”.
He said he did not want to wait until after Brexit “before getting on with our plans to take this country forward”.
Mr Rees-Mogg, who was at the meeting with the Queen, said this Parliamentary session had been one of the longest in almost 400 years, so it was right to suspend it and start a new session.