WASHINGTON (Reuters) - U.S. Deputy Attorney General Rod Rosenstein, who appointed Special Counsel Robert Mueller in May 2017 to investigate links between the Russian government and President Donald Trump’s campaign, said on Monday he was resigning from his post.

FILE PHOTO: U.S. Deputy Attorney General Rod J. Rosenstein speaks at the Los Angeles Crimefighters Leadership Conference in Los Angeles, California, U.S., February 7, 2019. REUTERS/Mike Blake

Rosenstein’s departure, effective May 11, was not a surprise. He had been expected to step down in March. The White House had no immediate comment, but noted that Trump had already nominated Deputy Transportation Secretary Jeffrey Rosen to replace him.

Rosenstein ended up staying on the job longer to help Attorney General William Barr manage the public release of Mueller’s findings from his 22-month investigation, which was completed on March 22.

In a letter to Trump, Rosenstein echoed two of Trump’s signature phrases, writing that he helped staff the department with officials “devoted to the values that make America great” and adding that “we always put America first.”

Mueller’s investigation did not establish evidence that Trump’s campaign illegally conspired with Moscow.

Mueller, in his final report, did not make a determination on whether Trump obstructed justice, but instead presented evidence on both sides.

After receiving the final report, Rosenstein and Barr made their own determination, finding there was insufficient evidence to charge the president.

“We enforce the law without fear or favor because credible evidence is not partisan,” Rosenstein wrote in his resignation letter.

Rosenstein, a Republican, was often criticized by Trump and his allies for appointing Mueller. He has also been involved in decision-making at the Justice Department that has been criticized by Democrats.

Democrats have directed most of their anger at Barr for how he chose to selectively release certain details of the Mueller report before making it public and for his decision to declare Trump had not obstructed justice.

But Rosenstein played a prominent role in weighing the evidence Mueller had gathered on obstruction and deciding that Trump should not be charged.

Last autumn, questions swirled about whether Trump might fire him, after the New York Times reported that Rosenstein had suggested in 2017 secretly recording Trump with a wire and recruiting Cabinet members to remove the president from office under the U.S. Constitution’s 25th Amendment.

Rosenstein has said the story was “inaccurate.” Despite stoking Trump’s ire, he remained on the job.

In a speech last week, he blasted “mercenary critics” and defended how the Mueller investigation was handled.

“If lawyers cannot prove our case in court, then what we believe is irrelevant,” he said.