Mark Zuckerberg is facing a lot of questions about Facebook’s policies, most of which involve handling user data. But there’s a running theme on the Republican side of the aisle: Facebook is censoring conservative content, particularly two pro-Trump vloggers who go by the names Diamond and Silk. Multiple legislators have asked about Lynnette “Diamond” Hardaway and Rochelle “Silk” Richardson, who complained that Facebook was limiting the reach of their videos, and were told their videos were “unsafe to the community.” Facebook later told reporters that the email was “inaccurate and not reflective of the way we communicate with our community,” but that hasn’t satisfied lawmakers.

Sen. Ted Cruz (R-TX) listed a series of alleged cases of Facebook censorship yesterday, including Diamond and Silk’s complaint. “To a great many Americans, that appears to be a pervasive pattern of political bias,” Cruz said. Zuckerberg denied the allegation but called it a “fair concern,” and Cruz moved on to questions about Palmer Luckey. But more lawmakers brought up the pair the next day. Rep. Joe Barton (R-TX) started his questioning by reading off a query he got through Facebook, saying he had “dozens” of similar ones. “Please ask Mr. Zuckerberg, why is Facebook censoring conservative bloggers such as Diamond and Silk? Facebook called them ‘unsafe to the community.’ That is ludicrous. They hold conservative views. That isn’t unsafe.”

Zuckerberg said that “in that specific case, our team made an enforcement error, and we have already gotten in touch with them to reverse it.” Rep. Fred Upton (R-MI) repeated Barton’s question in passing, and Rep. Marsha Blackburn (R-TN) asked whether Facebook manipulated algorithms to censor speech, jumping in angrily when Zuckerberg talked about automatically finding and banning terrorist content. “Let me tell you something right now. Diamond and Silk is not terrorism!” she exclaimed.

Diamond and Silk quickly condemned Facebook’s “unsafe” language, and Facebook had walked it back well before the hearing. But the case is the latest in a long series of fights over Facebook’s alleged anti-conservative bias, and it’s clear that Republican lawmakers aren’t going to drop the issue. Rep. Billy Long (R-MO) even asked a question he said was directly from the vloggers, going so far as to hold up a giant poster board with their picture and asking Zuckerberg to identify them. “Diamond and Silk have a question for you, and that question is: what is unsafe about two black women supporting President Donald J. Trump?”

Zuckerberg reiterated that “nothing is unsafe about that.” But Long castigated him for not being (in Zuckerberg’s words) “up to speed” on the issue, and warned him that Congress was “getting ready to overreact” with regulation. “I would suggest you go home and review all these other things people have accused you of today,” he said. “You’re the guy to fix this, we’re not. You need to save your ship.”

Update 1:30PM ET: Added statement from Rep. Long.