With less than 36 hours to go until the long-awaited vote, Mrs May will say, based on last week's Westminster drama, that she now believes MPs blocking Brexit is a more likely outcome than leaving without a deal.
Writing in the Sunday Express, Mrs May said: "You, the British people, voted to leave".
The PM has said failing to deliver on the result of the 2016 referendum would be "unforgivable" and a "catastrophe" for democracy.
An EU official said: "Should the prime minister survive and inform us that she needs more time to win round parliament to a deal, a technical extension up to July will be offered".
The deal has come under fire from across the political spectrum, with opponents of the European Union seeking a cleaner break and pro-European lawmakers pressing for a second vote on membership of the bloc.
Corbyn declined to say whether a Labour manifesto for a snap election would promise to deliver Brexit, arguing that this would be up to party processes, but strongly indicated his preference would be to depart with a deal that keeps the United Kingdom in a customs union and with access to the single market.
Opposition lawmakers have been asked to ensure they'll be present both for the vote on May's bill and a confidence vote the following day, regardless of whether they're ill, the Guardian's Sunday edition, the Observer, reported.
Under the Fixed-term Parliaments Act, Labour can call a no-confidence motion which would most likely prompt a general election if May lost it.
Brexit minister Stephen Barclay told BBC TV that persuading enough lawmakers to support the deal would be "challenging" but that even if it was rejected, he suspected parliament would ultimately support something "along the lines of this deal".
Ms Rudd said it was "right" for the government to make preparations for a no-deal Brexit, comparing it to wearing a seatbelt when driving a fast auto.
But officials said Brussels would be in listening mode, and take guidance from the prime minister as to the next steps should she suffer a heavy defeat as is widely expected.
Corbyn confirmed that he would not consider supporting the government in the meaningful vote on Tuesday, despite Theresa May's last-ditch attempts to garner support for her deal from members on the opposition benches.
"What Article 50 says is what 500 MPs voted for, backing up our vote in a referendum, backing up our vote in a General Election where 85 per cent of us voted for parties saying they would deliver Brexit".
The UK is poised to leave the EU on March 29, two years after it triggered Article 50, the exit clause in the EU's constitution, and kick-started arduous negotiations with European leaders over a divorce deal.