(CNN) Tensions are building inside the Justice Department as Deputy Attorney General Rod Rosenstein contemplates whether he will become a witness in the ongoing investigation into Russian meddling in the 2016 US elections.

Rosenstein, in office for less than two months, is the top Justice official overseeing the probe because Attorney General Jeff Sessions has recused himself.

But Rosenstein could end up recusing himself, too, Justice officials say, in part because he played a role in President Donald Trump's firing of FBI Director James Comey. The Comey dismissal could become part of a widening investigation into whether the President tried to interfere with the ongoing Russia probe.

Officials familiar with the matter describe friction on the Justice Department's fourth and fifth floors, home to the suite of offices belonging to the deputy attorney general and the attorney general, respectively, in part because of Rosenstein's handling of the Russia matter.

Rosenstein was among those who advised Sessions to recuse himself, according to officials briefed on the matter. Another official disputed that Rosenstein pushed for Sessions' recusal. But then Rosenstein made the surprise move to appoint Robert Mueller as special counsel to lead the Russia investigation, a development that people close to Sessions and Trump believe has worsened matters for everyone involved.

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