LONDON — For months, analysts have wondered when the grinding pressures of Britain’s withdrawal from the European Union would stretch political divisions and loyalties to the breaking point, possibly leading to a realignment of British politics.

That point may have come closer this week.

On Wednesday, three lawmakers quit Prime Minister Theresa May’s Conservative Party, joining eight rebels from the opposition Labour Party in a bold attempt to smash Britain’s entrenched two-party system for the first time in a generation.

It will not be easy. The group of 11 newly independent lawmakers have no policy platform, political organization or leader, and they will operate in an electoral system that makes it almost impossible for new parties to break through.

Still, analysts believe that conditions are ripe for a shift, amid public disenchantment at the handling of Brexit, fierce internal party rifts, and a perception that both main parties are pandering to their extremes.