After her plan was defeated by 344 votes to 286, Mrs May told MPs: “I fear we are reaching the limits of this process in this House.
“This House has rejected no deal. It has rejected no Brexit. On Wednesday it rejected all the variations of the deal on the table.
“And today it has rejected approving the withdrawal agreement alone and continuing a process on the future.
“This Government will continue to press the case for the orderly Brexit that the result of the referendum demands.”
Mrs May’s official spokesman subsequently said a general election was not in the national interest – but pointedly, did not rule one out.
The speech has caused uproar on Twitter from political analysts who have said the speech means she is likely considering calling another election.
Mrs May had previously made a last-ditch plea to MPs to get her withdrawal agreement over the line and deliver Brexit on May 22.
In a special sitting of the House of Commons on the day initially scheduled for the UK to leave the European Union, the Prime Minister told MPs: “This is the last opportunity to guarantee Brexit.”
Theresa May addresses MPs in the Commons
Mrs May was buoyed by declarations from hardline Brexiteers including Boris Johnson, Dominic Raab, Jacob Rees-Mogg and Iain Duncan Smith that they will vote with her in the division.
As MPs prepared to vote, Mrs May said: “If you want to deliver Brexit, this is the moment.
“If you are passionate about making sure the United Kingdom leaves the European Union, back this motion. If you care about our Union and want a deal that protects it, back the motion.
“If you want to honour the referendum, but want Parliament to shape our future relationship, back this motion.
DUP Brexit spokesman Sammy Wilson
“It’s the right thing for our country, it’s the right thing for our constituents.”
But victory still seemed likely to remain beyond her grasp, as the Democratic Unionist Party and a clutch of influential Leave-backing Tories made clear they will continue to oppose the agreement reached with the remaining 27 EU states in November.
DUP Brexit spokesman Sammy Wilson said the Northern Irish party’s 10 MPs will vote against the agreement because it “betrays the wishes of the vast majority of people who voted to leave”.
Mrs May’s comments immediately triggered widespread general election talk.
The Open University’s Dr Richard Heffernan told Express.co.uk: “The House as a whole can reject the preferred option if one emerges from Monday’s indicative vote and force a general election.
“The govt can refuse to take forward that preferred option. So No Confidence vote and a general election. SNP and Lab want a general election, so the Fixed Term Parliaments Act (FTPA) will be circumvented.
“An election is grounds for an extension, however long, even if participating in Euro elections. Have the general election the same day as the Euros. Postpone the locals until then. Clean house!!”
And Twitter users also began predicting another nationwide poll.
David Mundell’s tweet
One said: “MPs reject May’s EU withdrawal agreement – May fails again… time for the British people to now decide on this #PeoplesVote and #GeneralElection now please #Brexit”
SNP Westminster leader Ian Blackford told the Press Association: “I think there has to be a general election. The Government’s proposition is absolutely dead.
“The Prime Minister has absolutely no credibility.
“We should put this back to the people.”
Meanwhile Scottish Minister David Mundell posted: “@theSNP and Labour MPs gloat as the PM’s Deal voted down.
“And what are their solutions? A General Election, an independence referendum.
“Yet again politicking and self interest over the National interest.”
And under-pressure transport secretary Chris Grayling told Sky News “I think the last thing the country needs right now is a General Election.”
Even Jacob Rees-Mogg is reported to have backed Mrs May – to no avail
Others suggested a second referendum was on the cards.
Danny Wallace, 28, from Manchester, said: “I listened to what happened and Theresa May pretty much said she’s going to come out with a second referendum.
“That’s a bad idea, I think what most people wanted was what was on the table – leaving the EU under World Trade Organisation rules.”
Mr Wallace and two friends had spent the afternoon in Parliament Square to await the outcome of the vote.