BRUSSELS — From the start of the torturous negotiations over Brexit, as Britain’s exit from the European Union is known, the talks have followed an all too familiar dynamic.

The Europeans set the agenda; the British push for concessions or special deals, while trying to work out among themselves what they really want. The Europeans say no, sticking to a pretty hard line.

But now, with 85 percent of a deal completed, and the toughest issues remaining, European officials say they are increasingly worried that Prime Minister Theresa May’s government is so divided and fragile that it could collapse, scuttling a deal and inflicting damage on the Continental economy.

So the Europeans are now exploring ways to finesse their position, three senior European officials say, to sign a withdrawal agreement by the end of the year so it can be ratified by the end of March, when Brexit occurs regardless.