LONDON — The full weight of two and a half years of struggle was visible on Prime Minister Theresa May’s face when she appealed to her colleagues to let go of their passionate, polarized beliefs and support her plan to leave the European Union in a vote on Tuesday.

“This argument has gone on long enough,” she said. “It is corrosive to our politics. And life depends on compromise.”

If Mrs. May’s appeal for compromise has rung hollow, it is due in part to her own choices.

As she negotiated Britain’s departure from the European Union, she was secretive about her intentions, like a poker player holding her cards to her chest. Early on, she expended vast reserves of energy reassuring the hard-line faction of her party that she was on their side, declaring boldly that “no deal for Britain is better than a bad deal for Britain.”

By the time she revealed her true plan, presenting the country with a compromise that should have appealed to moderates, she had few reserves of trust or loyalty to draw upon.