LONDON — For all the talk of an epic conflict between the European Union and Britain over its planned withdrawal, known as Brexit, there are, in fact, several battles underway.

And right now the fiercest are in London.

On Thursday the British government pressed ahead with what was supposed to be one of the easy parts of quitting the 28-nation bloc, introducing a parliamentary bill that essentially cuts and pastes European Union law onto the British statute book to ensure continuity when Britain leaves.

But like almost everything about Brexit, this has turned out to be more complicated than it seemed. What at first appeared to be dry and technocratic legislation has become a political battleground, provoking protests from opposition parties, trade unions, the governments of Scotland and Wales and even some lawmakers from the Conservative Party of Prime Minister Theresa May.

That would be a tough challenge, even if the Conservatives were united over Brexit. But on Thursday hard-line, pro-Brexit Conservative lawmakers were organizing to resist moves to soften the economic impact of withdrawal by stretching it out — a stance the cabinet seemed to have finally agreed upon after months of feuding.