The Senate voted Tuesday 94-6 to confirm Rosenstein.
As the second-in-command under Attorney General Jeff Sessions, Rosenstein's March confirmation hearing focused largely on Sessions' own undisclosed discussions with the Russian ambassador to the US, Sergey Kislyak, and eventual recusal from Justice Department investigations regarding Russia.
Rosenstein's confirmation was never truly in doubt - although his confirmation was still contentious, as he refused to commit to appointing a special counsel to oversee investigations of alleged election meddling by Russian Federation.
A Justice Department spokesman did not respond to a question about when Rosenstein will be sworn in.
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"It is a very powerful reminder that there's mounting evidence of criminal wrongdoing in connection with Russian meddling and potential collusion between Trump associates and Russian wrongdoing", Blumenthal said.
The investigation, though, continued to dog Rosenstein's path to the upper ranks of the Justice Department. Chris Murphy supporting the nominee for deputy attorney general.
"How I would handle an investigation.is how I would handle any investigation", Rosenstein said. Rosenstein will now decide whether to appoint an independent prosecutor in that matter. Sessions recused himself from the investigation in March after failing to disclose he had met twice past year with Russia's ambassador to the U.S., Sergey Kislyak.
The deputy attorney general is responsible for day-to-day operations and oversight of the Justice Department's law enforcement agencies such as the Federal Bureau of Investigation. He was unanimously confirmed as US attorney in 2005 after being nominated by President George W. Bush and continued to serve under President Barack Obama.
He'll also help hire dozens of USA attorneys after President Trump asked for their resignation in March.