British Prime Minister Boris Johnson’s bad week got even worse Thursday when younger brother Jo walked away from his government post over their differing stances on Brexit.

It was clearly a difficult decision for Jo Johnson, who had returned to government as an education minister when his big brother replaced Theresa May as prime minister in July. Jo Johnson had quit May’s government last year and argued that Britain should have another vote over its decision to leave the European Union.

His pro-European credentials stood at odds with those of his brother’s, who became prime minister on a pledge to leave the EU by the Oct. 31 Brexit deadline come what may.

Jo Johnson — who, like his brother, has prominent blond hair — also said he will step down from Parliament rather than compete at the next election.

He said he was “torn between family loyalty and the national interest” and came to the conclusion that it was time for someone else to fill his shoes in Parliament and in the government.

The illustrious Johnson family is deeply divided over the wisdom of leaving the EU. Boris Johnson played a key cheerleading role in the 2016 Brexit referendum, helping convince a slight majority of the country to vote in favor of splitting. He is now quite willing to accept a “no-deal” Brexit, a position Jo Johnson rejects.

Sister Rachel Johnson, a journalist and TV personality, is in favor of keeping Britain within the EU — she tweets that the family doesn’t bring Brexit up at dinner to avoid ganging up on the prime minister.

Their 79-year-old father Stanley Johnson, an author and former Conservative member of the European Parliament, has switched sides and now backs leaving the EU, although he seems to focus more on environmental issues and wildlife protection.

Brother Leo Johnson tends to steer clear of politics but he has been known to retweet postings from people who favor remaining in the EU.

(AP)