But his record of the investigation on Russia was more complicated. In the tumultuous days following the dismissal of the president by Mr. Comey in May 2017, Mr. Rosenstein was upset and upset, fearing that the White House would have used it to justify the dismissal, said associates.

In meetings with senior law enforcement officials, he suggested secretly recording his conversations with Mr. Trump and invoking the 25th amendment to dismiss the president, according to people familiar with it. with the discussions and a note written by Andrew McCabe, then MP, FBI director.

Mr. Rosenstein finally sought to stem the chaos by appointing Mr. Mueller as a special advisor, but he consulted with virtually no one, according to three ministry officials who were not allowed to discuss the appointment.

Later, his work to protect the investigation of Mueller against the allies of Congress Trump, which the Democrats have accused of trying to undermine sensitive investigations, also attracted criticism. To calm the legislators, Mr. Rosenstein has made available a multitude of documents related to these investigations, steps against the reluctance of law enforcement to exchange information on investigations.

Senior law enforcement officials pointed out that under Mr. Rosenstein, the department had won one of its most critical battles with conservative lawmakers who had asked for the declassification of the law. a wiretapping application at the heart of the investigation on Russia. Despite pressure from congressional Republicans, the White House refused to release the document.

"Rod was in a really unusual position and was largely a firm hand," said Megan L. Brown, a lawyer at Wiley Rein, who worked at the Department of Justice with Mr. Rosenstein under George W.'s presidency. Bush.

A graduate of the University of Pennsylvania and Harvard Law School, Mr. Rosenstein worked in the Department of Justice for nearly 30 years before becoming Deputy Attorney General. At first, he was a lawyer in Washington and later a US lawyer for Maryland under the orders of Mr. Bush and President Barack Obama.