Oh, brother!

British Prime Minister Boris Johnson, who has been stymied by Parliament over his goal to pull the United Kingdom out of the European Union with or without an exit deal, suffered another defeat Thursday when his little brother quit the government and stepped away from his Parliament post.

“In recent weeks I’ve been torn between family loyalty and the national interest – it’s an unresolvable tension & time for others to take on my roles as MP & Minister. overandout,” Jo Johnson, a minister in his brother’s cabinet and a member of the Conservative Party, said on Twitter.

The prime minister noted the divisive nature of Brexit as he reacted to the announcement by his 47-year-old brother, whom he called a “fantastic guy.”

“Jo doesn’t agree with me about the European Union because, obviously, it’s an issue that divides families and divides everybody,” Johnson said. “But I think what Jo would agree is we need to get on and sort this thing out.”

Asked if he’ll resign like his brother, Johnson said he is “sworn to uphold” the Brexit referendum.

The Johnson family is torn on Brexit.

Their father, Stanley Johnson, voted to stay in the European Union but then embraced a divorce in 2017.

Sister Rachel Johnson, 57, was a former Conservative Party member who resigned in 2017 over its support of Brexit.

“The family avoids the topic of Brexit especially at meals as we don’t want to gang up on the PM!,” she wrote on Twitter after Jo’s resignation.

Another Johnson brother, Leo, the youngest of the brood, has backed holding another referendum on Brexit.

The prime minister, who took office in July after his predecessor Theresa May was brought down by Brexit, is determined to leave the European Union without a divorce deal on the Oct. 31 deadline.

But Parliament dealt Johnson several blows on Wednesday by voting to block his plan for a no-deal Brexit and his call for snap elections next month.

With Post wires