TOPSHOT - Britain's Prime Minister Theresa May arrives at the European Council in Brussels on October 17, 2018. - British Prime Minister Theresa May is due to address a summit of European Union leaders in which Brexit negotiations are expected to be top of the agenda. (Photo by EMMANUEL DUNAND / AFP)        (Photo credit should read EMMANUEL DUNAND/AFP/Getty Images)
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TOPSHOT - Britain's Prime Minister Theresa May arrives at the European Council in Brussels on October 17, 2018. - British Prime Minister Theresa May is due to address a summit of European Union leaders in which Brexit negotiations are expected to be top of the agenda. (Photo by EMMANUEL DUNAND / AFP) (Photo credit should read EMMANUEL DUNAND/AFP/Getty Images)
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WINDSOR, ENGLAND - APRIL 17: The Duke of Edinburgh's coffin, covered with His Royal Highness's Personal Standard is carried to the purpose built Land Rover during the funeral of Prince Philip, Duke of Edinburgh at Windsor Castle on April 17, 2021 in Windsor, England. Prince Philip of Greece and Denmark was born 10 June 1921, in Greece. He served in the British Royal Navy and fought in WWII. He married the then Princess Elizabeth on 20 November 1947 and was created Duke of Edinburgh, Earl of Merioneth, and Baron Greenwich by King VI. He served as Prince Consort to Queen Elizabeth II until his death on April 9 2021, months short of his 100th birthday. His funeral takes place today at Windsor Castle with only 30 guests invited due to Coronavirus pandemic restrictions. (Photo by Adrian Dennis/WPA Pool/Getty Images)
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(CNN) —  

Next week, Britain’s House of Commons will vote on whether Prime Minister Theresa May’s Brexit deal should go ahead. Given that May’s Conservative party has no overall majority and too many of her own members of parliament are against it, she was already braced for defeat in that vote. But after extraordinary scenes in the Commons on Tuesday evening, that likely defeat could also mean the end of her premiership.

In little more than an hour on Tuesday, the government suffered three defeats on its Brexit plans. The first two were embarrassing enough: MPs voted that the government was in contempt of parliament, the first time that’s happened in British history. By refusing to publish in full the legal advice on the Brexit deal agreed with the European Union last month, ministers were found to have breached the sovereignty of parliament – and parliament has fought back and reasserted its control.

The third defeat, while more technical, was still hugely significant because it means that next Tuesday, MPs from all parties can decide not only to reject May’s deal but instruct the government on what to do next.

Until now, the Prime Minister has warned MPs that voting down her Brexit plans will mean a no-deal departure from the EU by default. That scenario is relished by some hardline Brexiteers who want out of the EU at any cost. But it has spooked financial markets, businesses and the Bank of England, who have warned that it will come at a severe economic price to Britain.

But Tuesday’s scenes made one thing clear: MPs are likely to use their new-found power to block a no-deal outcome. The hardest of all Brexits seems off the table.

After that, everything seems up for grabs. Proposals are already being put forward for a softer Brexit. For example, Britain could adopt a model similar to Norway, which is not a member of the EU but pays for access to its single market. The campaign for a second national referendum, or People’s Vote, is gathering momentum – one that could lead to no Brexit at all. But the likely defeat next Tuesday could also see the opposition Labour party call for a vote of no confidence in the government. If May lost that vote, a general election could follow.

Labour says it is ready for another election – the second in less than two years. Significantly, the Northern Irish DUP party, which has an agreement to support the Conservative minority government in order to keep it in power, has made clear it is also ready for an election. Its leader in Westminster, Nigel Dodds, said on Tuesday: “We will happily go to the electorate and put our views to the people if needs be.”

The DUP opposes to May’s Brexit deal because it holds out the prospect of Northern Ireland operating on different regulatory and customs arrangements from the rest of the UK, in the event that future negotiations on a trade deal between London and Brussels collapse.

On Wednesday, when the government was forced to publish that legal advice in full, it became clear that the DUP was right to be wary. Under the “backstop” or insurance arrangement, Northern Ireland and the rest of the UK would be subject to separate customs arrangements, and goods passing between Britain and Northern Ireland would be have to undergo customs checks. The DUP, a staunchly unionist party, see this as effectively breaking up the union between Great Britain and Northern Ireland.

Since taking over as Prime Minister in July 2016 after the turmoil of the Brexit vote, May has portrayed herself as a dutiful, businesslike leader acting in the national interest. Despite several ministerial resignations and letters of no confidence from her MPs, the PM has been resilient in the face of such turbulence. Her aides have long insisted May is not the type to quit when the going gets tough.

Those around her are also fearful that if she were to resign, her successor would be someone who wants a harder Brexit – such as Boris Johnson, the former Foreign Secretary, or backbench Euroskeptic Conservative MP Jacob Rees-Mogg. She has much more to protect than her own reputation.

And yet, Tuesday evening’s events may have changed those assumptions. When the Prime Minister addressed the Commons minutes after those three bruising defeats, her tone was typically determined – but this time, her speech had a valedictory air to it.

“I have spent nearly two years negotiating this deal,” she said. “If I had banged the table, walked out of the room and delivered the very same deal that is before us today, some might say I had done a better job. But I didn’t play to the gallery. Don’t let anyone here think that there is a better deal to be won by shouting louder.”

This is the heart of May’s message to her own and opposition MPs – that there is no better deal to be done with Brussels. After events in the Commons this week, MPs clearly think otherwise, and are likely to make their position clear next Tuesday. A large-scale defeat would not only mean the end of May’s Brexit plans, but it would amount to a loss of confidence in her premiership.

After her government has been held in contempt, and with such a crushing defeat on the most important policy of her premiership, it is hard to see how May would be able to remain in Downing Street.