UK Prime Minister Theresa May drew widespread criticism on Monday after delaying a parliamentary vote on the Brexit deal she appeared certain to lose heavily.
The Opposition Labour Party said Britain now no longer had a functioning government.
"The government has decided Theresa May's Brexit deal is so disastrous that it has taken the desperate step of delaying its own vote at the eleventh hour," Labour leader Jeremy Corbyn said in a statement.
"We don't have a functioning government ... Labour's alternative plan for a jobs first deal must take centre stage in any future talks with Brussels."
Scotland Chief Minister Nichola Sturgeon said the Brexit deal should have gone before parliament immediately so that it could be voted down.
The postponement, she said was "an act of pathetic cowardice by a government now collapsing under utter chaos".
The deputy leader of the DUP, the N.Ireland party propping up the conservative government, said he would not welcome a no-deal Brexit, but was not afraid of one.
The Northern Irish party said May needed to renegotiate her Brexit divorce, or be replaced by someone willing to change course.
"What (the EU) need to be faced with is either somebody who is going to really make it clear they are prepared to walk away, or a different Theresa May who will make that explicit," Nigel Dodds told BBC TV.
"If anyone needs any further lesson or demonstration on how not to negotiate, look at the shambles today of the government in the House of Commons having to pull a vote on something that they said was the only way forward."
Ireland's Prime Minister Leo Varadkar reiterated the EU position that Britain cannot partially renegotiate the Brexit withdrawal deal which Mrs May agreed with the European Union, though some clarification might be possible.
"The withdrawal agreement, including the Irish backstop is the only agreement on the table. It's not possible to reopen any aspect of that agreement without reopening all aspects," Varadkar told reporters.
"I have no difficulty with statements that clarify what's in the withdrawal agreement but no statement of clarification can contradict what's in the withdrawal agreement," Varadkar added when asked if Dublin would support a statement from the EU clarifying issues around the so-called Irish backstop.
Mrs May is due to address the House of Commons at 4.30pm (Malta time) amid renewed calls for a second referendum, calls which were strengthened after the European Court confirmed that the UK can drop Brexit.