Rod Rosenstein is leaving his post as the U.S. Justice Department's deputy attorney general effective May 11, according to a resignation letter submitted Monday.

“Our nation is safer, our elections are more secure, and our citizens are better informed about covert foreign influence efforts and schemes to commit fraud, steal intellectual property and launch cyberattacks,” Rosenstein wrote.

Rosenstein ended his letter with a nod to the media and truth: “We enforce the law without fear or favor because credible evidence is not partisan, and truth is not determined by opinion polls. We ignore fleeting distractions and focus our attention on the things that matter, because a republic that endures is not governed by the news cycle.”

Rosenstein's resignation caps an often-contentious time at Main Justice, where he had been a target of criticism by President Donald Trump. Rosenstein appointed Robert Mueller III as the special counsel leading the investigation Russia's interference in the 2016 presidential election. Trump also tried unsuccessfully to get former White House counsel Don McGahn to push Rosenstein to fire Mueller.

Rosenstein was expected to bring a dose of stability to the Justice Department following the sudden firings of 46 Obama-era U.S. attorneys, failed attempts to defend the president's immigration executive orders, and former U.S. Attorney General Jeff Session's recusal from overseeing Mueller's probe.

Where's Rosenstein going? He hasn't said. As the National Law Journal reported in January, Rosenstein will have options:

Rosenstein hasn't worked in private practice for more than 30 years. In 1987 he was a summer associate at President Richard Nixon's now-defunct former law firm, Mudge Rose Guthrie Alexander & Ferdon, and he spent the following summer at Philadelphia's Schnader Harrison Segal & Lewis. He hasn't given any indication that he plans to give Big Law another go, but history suggests he wouldn't have trouble finding a home at any number of firms—not to mention companies or universities.

Rosenstein's departure was expected, as he indicated he would leave Main Justice after the conclusion of the special counsel's investigation. Rosenstein's would-be successor, former Kirkland & Ellis partner Jeffrey Rosen, is awaiting confirmation by the U.S. Senate. Rosen would leave his post as the No. 2 at the U.S. Transportation Department to be the No. 2 at the Justice Department under Attorney General William Barr.

Read the Rosenstein resignation letter below:

Mike Scarcella contributed to this report.