On Wednesday, the Prime Minister was defeated in the House of Lords
in a key vote on Britain's departure from the European Union. Peers rejected a proposal to withdraw Britain from a customs union with the European Union after Brexit without a proper debate in Parliament.
The Lords is often seen as an outdated body -- unelected and aging -- but it has the power to inflict damage and cripple government policy when it sees fit. What's more, the seniority of members voting against May was considerable: they included five former Cabinet ministers, several former junior ministers and every living former Cabinet secretary -- the most senior official in the British government. A second defeat for the government swiftly followed the first.
The vote on the customs union is crucial because it marks what many see as the dividing line between a hard and soft Brexit. May's plan is to withdraw the UK from both the EU single market and any customs union with the EU, and is one of her negotiating red lines. Yet opponents regard this "hard Brexit" plan as detrimental to the British economy, and want the UK to remain in some form of customs union with Brussels.
But the customs union vote was also only the beginning of what will likely be a war of attrition on all aspects of Brexit between the Lords, where May does not have an overall majority, and the Commons, where the government's majority only exists because of the smaller DUP party of Northern Ireland. In the next few months, both houses of Parliament are likely to take apart her plans for a hard Brexit.
Later this month, the Lords are likely to defeat the government on plans to fix the date and time of Brexit for 2300 GMT on March 29, 2019, and on issues related to the Irish border.
While May can expect to overturn some votes when the legislation returns to the Commons, this is not guaranteed: several of her own MPs plan to rebel against the government, while the DUP could decide to pull support for the Prime Minister if plans for the Irish border post-Brexit are not to their liking.
There is alarm in both legislative houses over plans to implement a "no deal" Brexit if the carefully negotiated agreement between Britain and the EU is rejected by the UK parliament. May claimed in a speech last year that "no deal is better than a bad deal," but opponents insist this would damage the economy, inviting costly tariffs for businesses trying to trade with the rest of the world.
The timing of the defeat was made all the more awkward because it coincided with the year anniversary of May's decision to call a snap election -- which led to her losing her overall majority.
It also came as May's predecessor, David Cameron, gave an interview to CNN's Christiane Amanpour
in which he said he had no regrets over calling a referendum on EU membership, adding that he "wished my successor well." The Prime Minister is going to need more than well-wishing if she is to survive the next year in Downing Street without being forced from office over Brexit.
So what can she do? A final deal on Brexit between the UK government and Brussels is expected by October.
This deal will need the approval of the UK Parliament before it can be implemented. Yet the House of Lords has started to reject a hard Brexit, and it is likely that the House of Commons, when it gets its chance to vote, will too.
If she wants Britain to leave the EU by March 29, 2019 she needs to start negotiating with MPs and peers and make concessions on the most contentious points, including membership of a customs union, to soften Brexit.
This would not go against the wishes of the British people, who voted for Brexit on a referendum question that gave no details on customs union membership. Otherwise, successive parliamentary defeats will mean her biggest problem is being able to hold onto office.