The prime minister battles on, beset on all sides in parliament. Many say she has only herself to blame for the shambles after failing to win over pro-EU and pro-Brexit rebels in her Conservative party or to persuade opposition lawmakers to back her Brexit plan. May miscalculated badly in 2017 when she called an early election in the hope of securing a larger parliamentary majority.
Instead, she finds herself at the mercy of the Democratic Unionists (DUP), a hard-line unionist party that is refusing to back the deal so laboriously hammered out with the European Union. She is also not short of opponents within her own Conservative party. The prime minister has been putting in 20-hour days in an attempt to haul the ship of state onto her chosen course.
The head of the official opposition Labour Party, Jeremy Corbyn senses his chance in another early election and aims to bring down the government. Corbyn, 69 and an old-school leftist, has drawn many young supporters to the party, but he has also come in for sharp criticism from Labour members of parliament. During the campaign for the 2016 referendum on EU membership he backed remaining in the bloc, but he refuses to join calls from within Labour for a second plebiscite. Some believe that Corbyn secretly wants the country to leave the EU.
With his oversized double-breasted suits, sharp hair parting and round glasses, Jacob Rees-Mogg is a caricature of an upper-class English gentleman. A socially conservative Roman Catholic, Rees-Mogg has been on the back benches since his election to parliament in 2010. He wields considerable power as the head of a group of around 80 hard-line proponents of Brexit within the party.
In December, he led Conservative lawmakers in urging a vote of no confidence in May. She emerged to fight another day. Rees-Mogg has urged people not to fear a hard Brexit - Britain leaving the bloc without a deal - if May fails to get her deal through parliament. A man with a considerable fortune and a classical education who occasionally tweets in Latin, Rees-Mogg has never cooked or changed a nappy for his six children - and is proud of the fact.
While the former head of the Northern Irish government, DUP leader Arlene Foster, does not sit in parliament in London, she wields considerable power behind the scenes.
Foster experienced the province's "Troubles" at close hand - her father was a police officer who was shot at by the Irish Republic Army. The unionist party holds just 10 seats, but they have propped up May's minority government with support on key votes.
The fact that the prime minister aims to whip her Brexit deal through parliament without DUP support is an indication of the desperation in the government.
Foster and her party colleagues may yet change their minds, perhaps with the aid of a promise of more funds for Northern Ireland, and the DUP is under increasing pressure in the province from business interests seeking to avoid a hard Brexit.
Former attorney-general Dominic Grieve is a champion of parliamentary sovereignty and is regarded as the legal super-brain among pro-EU Conservative members of parliament. Assisted by around a dozen like-minded members of the party and backed in votes by opposition lawamkers, he was able to compel May to place her Brexit deal before the House of Commons, parliament's main elected house.
Tuesday's vote is seen by some as the endgame - or at least the beginning of the endgame - in a battle between government and parliament. Grieve has thrown his weight behind calls for a second Brexit referendum.
But he and other Conservatives would see May's current deal as the lesser evil, compared to crashing out of the EU without a deal.