(CNN) President-elect Donald Trump is expected to nominate Baltimore US Attorney Rod Rosenstein for deputy attorney general, according to people close to the Trump transition.

Rosenstein is being picked for a key post to help run the Justice Department under Sen. Jeff Sessions, who is anticipated to win Senate confirmation as attorney general in the coming weeks.

Rosenstein is the longest serving US attorney at the Justice Department, having won unanimous Senate confirmation to his current post in 2005 under the administration of President George W. Bush. He's well-regarded in the department and stayed on as the top federal prosecutor in Baltimore under the Obama administration.

The then-Democratic-controlled Senate refused to confirm his 2007 nomination to the Fourth Circuit Court of Appeals.

Rosenstein declined to comment.

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