I mean, it was embarrassing,” Steve Bannon said on Monday, referencing Elon Musk’s tweets over the weekend when he said the H-1B visa program needed to be “reformed.”

Less than a month before Donald Trump returns to office, two of his most ardent allies have plunged into a fierce online debate over immigration, specifically the government’s visa program that allows American companies to hire so-called “highly skilled” foreign workers.

Donald Trump has backed Elon Musk in supporting visas for skilled migrants. The president-elect waded into a row that has split the Republican party by defending H1B visas, which permit highly-educated foreigners to work in the US for up to six years.