LONDON — Struggling to secure support for a minority government, Prime Minister Theresa May of Britain was expected on Wednesday to present a scaled-down legislative program that would prioritize Britain’s withdrawal from the European Union and would jettison policies likely to struggle to pass in Parliament.

Mrs. May, who has been trying to secure a deal with 10 lawmakers from the Democratic Unionist Party in Northern Ireland, needs their support after her Conservative Party lost its parliamentary majority in a general election two weeks ago.

The government’s legislative agenda will be laid out on Wednesday in the Queen’s Speech to Parliament. It had originally been scheduled for Monday but was postponed because of the political uncertainty.

Mrs. May is fighting for her political life. Not only has she been blamed by many in the Conservative Party for a disastrous election campaign but she was also widely judged to have mishandled the aftermath of a devastating and deadly fire at a London high rise last week.

Talks with the 10 lawmakers from the D.U.P. have proved much harder than expected. But even though Mrs. May’s position remains fragile, most analysts believe that she is likely to secure their support one way or another.

The D.U.P., which has strong Protestant roots, has a major incentive to find common ground with Mrs. May: Without its help, Mrs. May’s government could fall, and power could pass to the opposition Labour Party of Jeremy Corbyn, who has a history of close ties to Irish Republicans.

The crucial test will come next week, when lawmakers are to vote on the program in the Queen’s Speech.

Even if Mrs. May were to prevail, as expected, she would still struggle to pass contentious legislation. That being the case, her legislative program on Wednesday is expected to drop several measures that had once been centerpieces of her political agenda.

That means that she is likely to abandon proposals for more grammar schools, which use tests to determine admissions, and that there will most likely not be a mention of plans to require older people to pay more of the costs for long-term care at home — a proposal described by critics as a “dementia tax.”

In that respect, the Queen’s Speech is expected to highlight the extraordinary speed with which Mrs. May’s fortunes have declined. At the start of the election campaign, she was well ahead in opinion polls and was expected to secure a victory large enough to reshape British politics. But much of that support has evaporated in recent weeks.

The speech is expected to reflect Mrs. May’s desire to make Britain’s withdrawal from the European Union, known as Brexit, her top priority, with several bills intended to provide the legislative framework for the move.

That approach presents its own perils, however, because the general election failed to deliver an endorsement of the clean break with the bloc that she wanted — one that prioritizes control of immigration over economic interests.

Although the Labour Party accepted the outcome of the referendum on withdrawing from the European Union, it wants to keep closer economic ties to the bloc and it could try to obstruct crucial parts of the government’s Brexit-related plans.

Yet if Mrs. May softens her stance on withdrawing from the bloc to accommodate pro-Europeans worried about the British economy — including some members of her own cabinet — she risks a rebellion from leading supporters of the withdrawal. That would include possible successors like Boris Johnson, the foreign secretary, and David Davis, the cabinet minister responsible for negotiating Britain’s exit from the European Union.