The Mueller report, set to be released in redacted form on Thursday, will be a test of Attorney General Bill Barr’s integrity. Many critics expect him to flunk it. “I don’t trust Barr,” House Speaker Nancy Pelosi told the Associated Press last week. “I trust Mueller.” Some have even accused Barr of a cover-up, a case bolstered by reporting that special counsel Robert Mueller’s findings may be more damning for President Donald Trump than Barr had suggested in his summary to Congress last month.

A notable exception to this discontent is Rod Rosenstein. The deputy attorney general appointed Mueller nearly two years ago, and since then has defended the Russia investigation’s legitimacy from presidential and congressional attacks. Over the past few weeks, he’s used that credibility to defend his boss as he wraps up the probe. “[Barr] knows the history, he understands the issues, he respects the employees, and he will defend the principles,” Rosenstein wrote for Time’s list, released on Wednesday, of the year’s 100 most influential people. “With Bill Barr at the helm, the rule of law is secure.”

This presents a tricky quandary for Barr’s critics. Rosenstein is perhaps the only current official in the Justice Department with the credibility among Trump’s opponents to defend Barr. (Mueller could as well, but he’s not prone to public comments.) While figures like former FBI Director James Comey have argued that Barr should get the benefit of the doubt, Rosenstein’s knowledge of Mueller’s findings lends authority to that view. But his staunch defense of Barr presents its own risks for the deputy attorney general. Giving Barr’s actions the imprimatur of legitimacy only works if they turn out to be legitimate in the long run.

Barr’s actions so far have not inspired much confidence in his independence from the White House. In congressional testimony last week alone, he suggested that federal agents may have illicitly spied on the Trump campaign during the last presidential election. Barr later backpedaled on the allegation, but the damage was already done. Trump crowed on Twitter that he had been vindicated by Barr’s statements. Top Democrats wasted no time in airing their own grievances.

“Mr. Barr knows how counter-intel investigations work,” Virginia Senator Mark Warner, the top Democrat on the Senate Intelligence Committee, said in a statement. “He knows there was ample evidence of Russian attempts to infiltrate the Trump campaign and that the FBI took lawful action to stop it. Giving a wink and a nod to this long-debunked ‘spying’ conspiracy theory is irresponsible.” California Representative Adam Schiff, who chairs the House Intelligence Committee, said Barr’s assertions “strikes another destructive blow to our democratic institutions.”