LONDON — With the clock ticking down toward last-minute talks in Brussels on Britain’s withdrawal from the European Union, Prime Minister Theresa May this weekend took another step away from hard-line anti-Europe lawmakers in her Conservative Party and sought to portray herself as committed to compromise talks that stalled last week.

But opposition Labour leaders on Sunday maintained that Mrs. May had not yet bent to any of their demands on the withdrawal, known as Brexit. And whatever overtures she makes to Labour, analysts said, she will struggle to guarantee that her successor as prime minister or a future Parliament will not rip up any compromise deal — a major sticking point in the cross-party talks.

Mrs. May this week was expected to seek another delay to Britain’s departure from European leaders who have expressed anger at her reluctance to change strategy only days before they were to meet to consider her request. She is also trying to pressure Labour lawmakers who may be searching for an excuse to back a deal to avoid being seen as thwarting Brexit.