Rosenstein, 52, won unusual bipartisan support on the strength of his crime-fighting efforts as the U.S. attorney for Maryland for the last 12 years. He was confirmed as deputy attorney general by a vote of 94-6.
Normally the deputy has a low public profile, but Rosenstein will not have that luxury: Atty. Gen.
It will fall to Rosenstein to decide whether to file criminal charges against any of Trump's aides, to drop the case entirely or to hand it off to an independent prosecutor.
At his Senate confirmation hearing March 7, Rosenstein refused to say whether he would be willing to bring in a special counsel, saying he wouldn't make judgments in advance.
But he said he had "no reason to doubt" the conclusions of U.S. intelligence agencies that Russian authorities sought to influence the presidential race. He also said he believed the Justice Department could handle the most politically complicated cases without fear of compromise.
During the hearing, Rosenstein referred to his work in the 1990s in the independent counsel investigation of President
Rosenstein was involved in separate questioning of both Clintons, who never were charged with a crime. More than a dozen others were charged and convicted, including the governor of Arkansas.
Rosenstein has spent 27 years at Justice, getting an early job as a senior aide to a deputy attorney general. As U.S. attorney, he supervised a broad range of criminal prosecution.
He first was nominated to the post by President
As Sessions' top deputy, Rosenstein will be responsible for using Justice Department resources to step up enforcement of immigration laws, a Trump administration priority.
Sessions already has instructed all U.S. attorney's offices to be more aggressive about filing criminal charges against people who cross the border illegally, and he has threatened to cut off department grants to so-called sanctuary cities unless they cooperate with immigration agents.
Jamie Gorelick, who served as deputy attorney general from 1994 to 1997 under the Clinton administration, praised Rosenstein at an ethics conference Monday. She said the department would remain in experienced hands.
Sessions "picked someone who grew up in the department and knows how cases are decided, and should be decided," she said.