LONDON - Brexit could be reversed if lawmakers reject the government’s exit deal, British foreign secretary Jeremy Hunt said on Sunday after two major eurosceptic factions in parliament warned that Prime Minister Theresa May was facing a heavy defeat.

Just 19 days before the United Kingdom is due to leave the EU on March 29, May is scrambling - so far unsuccessfully - to secure last-minute changes to an EU exit treaty before parliament votes on Tuesday on whether to approve the deal. If she fails, lawmakers are expected to force May to seek a delay to Brexit which some fear could see the 2016 decision to leave the bloc reversed. Others argue that without a delay Britain faces an economic shock if it leaves without a deal.

“We have an opportunity now to leave on March 29 or shortly thereafter and it’s important we grasp that opportunity because there is wind in the sails of people trying to stop Brexit,” Hunt told the BBC. “We are in very perilous waters.”

The United Kingdom’s labyrinthine crisis over EU membership is approaching its finale with an extraordinary array of options including a delay, a last-minute deal, no-deal Brexit, a snap election or even another referendum. The ultimate outcome remains unclear, though most diplomats and investors say Brexit will define the United Kingdom’s prosperity for generations to come.

The government has previously tried to use the risk of Brexit being reversed as a way to convince eurosceptics to back May’s deal despite their deep reservations about it. “If you want to stop Brexit you only need to do three things: kill this deal, get an extension, and then have a second referendum. Within three weeks those people could have two of those three things ... and quite possibly the third one could be on the way.”

Nigel Dodds, deputy leader of the Democratic Unionist Party (DUP) which props up May’s minority government, and Steve Baker, a leading figure in the large eurosceptic faction of her Conservative party, warned “the political situation is grim”.

“An unchanged withdrawal agreement will be defeated firmly by a sizeable proportion of Conservatives and the DUP if it is again presented to the Commons,” they wrote in the Sunday Telegraph. The Sunday Times said May was battling to save her job as aides were considering persuading her to offer to resign in a bid to get the deal approved. The newspaper also said cabinet ministers have spoken about whether to insist she goes as early as this week.