Sessions faced heavy criticism from the president after recusing himself from overseeing Robert Mueller’s investigation into whether Russia meddled in the 2016 presidential election, as ethical questions plagued the attorney general over his role in the Trump campaign. But Whitaker may end up in a similar situation, presenting ethical problems of his own based information found on his Twitter account alone.

Whitaker, who has been called a Trump loyalist, has been very vocal about his criticism of Mueller and the investigation—which in his new role he will now oversee—on Twitter.

For instance, Whitaker commented in opposition of proposed legislation that would protect special counsel such as Mueller from White House pressure. His comments on the topic are problematic considering that in Whitaker’s role as acting attorney general, he would have the power to fire Mueller.

This would be a mistake. Cannot have anyone unaccountable in executive branch. Already protected enough. https://t.co/M2FfdMknI3

— Matt Whitaker 🇺🇸 (@MattWhitaker46) July 27, 2017

Whitaker’s Twitter account offers multiple public statements about the probe. Whitaker’s most damning Tweet is a self-promotion of an opinion piece he wrote for CNN, in which he claims that the Mueller investigation is going too far. In the piece, he claims that Trump and his family’s finances should be off limits in the Mueller investigation.

My opinion piece today "Mueller's Investigation of Trump is going too far" https://t.co/Q0IXwg06BW

— Matt Whitaker 🇺🇸 (@MattWhitaker46) August 6, 2017

Hours later, he also tweeted out an opinion piece, written by another lawyer, that encouraged Trump’s attorney not to cooperate with Mueller.

Worth a read. "Note to Trump's lawyer: Do not cooperate with Mueller lynch mob" https://t.co/a1YY9H94Ma via @phillydotcom

— Matt Whitaker 🇺🇸 (@MattWhitaker46) August 7, 2017

Days later, Whitaker posted an eyebrow-raising tweet in which he seems to have sarcastically compared the legal teams for both Trump and Mueller as being on either side of a knife fight.

Like going to a knife fight with a stick of butter. LOL. That's funny. Kinda. https://t.co/QWv7s19CrM

— Matt Whitaker 🇺🇸 (@MattWhitaker46) August 10, 2017

Later that day, Whitaker continued to criticize Mueller, as investigators questioned Trump’s former campaign manager Paul Manafort.

One thought, is Mueller trying to catch #Manafort in a "lying to Congress" case to exert pressure being day after interview with staffers? https://t.co/GFi2mu77hZ

— Matt Whitaker 🇺🇸 (@MattWhitaker46) August 10, 2017

Trump said in a tweet that a permanent replacement for Sessions will be nominated at a later date. It is currently unclear if Whitaker is being considered for that position.