Asked about the comments on Wednesday, the Brexit Secretary Stephen Barclay said the prime minister was still "committed to leaving on the 29th March", but did not rule out an extension altogether.
Comments by May's chief Brexit negotiator, Olly Robbins, overheard by an ITV correspondent at a hotel bar in Brussels have done little to boost trust among lawmakers.
The group, including Labour MP Yvette Cooper and Tory former minister Sir Oliver Letwin, have said they are ready to table an amendment enabling parliament to force ministers to seek a delay if there is no deal in place.
The prime minister said that if no deal is reached by February 26, the government will make a statement and table an amendable motion for MPs to vote on the following day.
But members of the backbench European Research Group say that it effectively endorses another amendment approved by MPs the same day, which rules out no-deal but is not binding on the Government. Only six of 40 European Union trade deals are on course to be rolled over in time for Brexit, The Sun newspaper reports.
She said it was possible to pass Bills "quite quickly" with "good will" from the Commons and Lords, but added: "It's just not possible to say how quickly it could be done, but obviously it depends on the way in which there is adequate debate on the meaningful vote and that's what the Prime Minister is determined to do".
The leader of the opposition wrote a letter to the Prime Minister last week setting out the demands she would need to meet in order command the support of Labour MPs for her deal.
"What are these negotiations at a "crucial state" raised in the House of Commons?"
With less than 50 days to go to Brexit day on March 29, British firms still have no idea what the country's new trading relationship with the European Union will look like, so they're taking a safety-first approach.
Parliament overwhelmingly rejected it in a vote on January 15, marking an historic defeat for the prime minister.
Amid the labyrinthin plots and counterplots of Brexit, the United Kingdom's most significant political and economic move since the Second World War, some major investors, such as Ford Motor Co., are trying to work out whether to shutter U.K. production. But I'm not the only person in Westminster this week to be wondering whether after many, many, many months of private conversations where this possibility was discussed, in the next couple of weeks, maybe even in the next couple of days, something that actually is critical is going to start happening.
The EU says the backstop is vital to avoiding the return of border controls in Ireland and has refused to reopen the Brexit divorce deal, though May insists she can get legally binding changes to replace the most contentious parts of the backstop.
With 45 days to go however, Mr Grieve warned time was running perilously short under the terms of the Constitutional Reform and Governance Act which requires 21 sitting days before the ratification of any worldwide treaty.
Labour leader Jeremy Corbyn suggested she was "running down the clock" on Brexit in the hope that MPs will be "blackmailed" by the fear of a no-deal scenario into supporting a "deeply flawed" agreement.
MEPs, meanwhile, are to vote today on laws to prevent disruption for airlines and hauliers in the case of a no-deal Brexit.