But supporters said the vote - of 303 to 296 - showed there was now a clear majority of MPs who would oppose a no-deal if Mrs May can not, as many expect, win the backing of the Commons for her agreement.
The report was backed by Lord Kerr of Kinlochard, a former head of the diplomatic service who helped draft the Article 50 withdrawal process, who said he believed the European Union would "willingly" agree to a postponement of the March 29 Brexit date to allow a fresh referendum.
Britain's parliament has dealt Prime Minister Theresa May's government a narrow defeat by passing an amendment created to put roadblocks in place to make a "no-deal" Brexit more hard.
Boris Johnson, who helped lead the Brexit campaign, said that voters would not be scared into backing a poor deal.
London police say they have increased their presence outside Parliament after some 55 lawmakers complained about verbal abuse as the Brexit debate intensifies.
In a two-way choice, 64 percent of grassroots members would opt for a "no-deal" Brexit on 29 March, with just 29 percent preferring the plan Theresa May has negotiated.
This is a breaking news story and will be updated.
The "war game" was criticised by lawmakers as a waste of time and money and mocked on Twitter as "a fake traffic jam.to show the European Union we are ready for no deal".
Ahead of the visit, he said: "The Government is spending plenty of taxpayers money preparing for a no-deal Brexit but it's very clear it is not taking seriously the disruption that would take place".
What happens if MPs fail to force May back within three days?
Without some movement from Brussels, Mrs May is expected to lose the division, which was postponed in December when it became clear that the Government would be defeated.
Downing Street insisted the amendment - tabled by senior Labour MP Yvette Cooper and Tory former cabinet minister Nicky Morgan - was no more than an "inconvenience" which would not prevent the Government collecting taxes.
"Todayâs trial can not possibly duplicate the reality of 4,000 trucks being held at Manston airport in the event of a no-deal Brexit", the RHA's chief executive Richard Burnett said in a statement.
For now it seems likely that Number 10's inevitable efforts to leverage this vote to persuade Brexiteers to accept the deal will not work next week at least. We all want to have a fruitful profitable relationship with the United Kingdom in the future so the backstop is just a last resort solution.
"The majority in this House will sustain itself, and we will not allow a no-deal exit to occur on March 29", he said.
A business minister has threatened to resign from the Government if it is necessary to stop a no-deal Brexit.
"These are political assurances but there's nothing more we can do".
The EU, for its part, has insisted that the withdrawal agreement can not be renegotiated but has made clear the backstop is meant only as a temporary measure of last resort.
How to watch wild-card Sunday of Chargers-Ravens and Eagles-Bears
But the missing kicker left the Seahawks no good options on an onside kick with 1:18 remaining. But his kick took a double deflection and fell harmlessly into the end zone. "West Coast kick.