Mr Rosenstein verbally resigned to White House Chief of Staff John Kelly, Axios reported, citing an unidentified source with knowledge of the matter.
A second source told Axios that Rosenstein is "expecting to be fired" so he plans to step down.
Donald Trump faces mounting pressure from the investigation by special counsel Robert Mueller, who is looking into Russia's role in the 2016 presidential election.
Mr Rosenstein assumed supervision of the probe after his boss,...
source: Express