Story highlights "I certainly have some very specific questions about the timeline," Peters said

Rosenstein doesn't see a need at this point for a special prosecutor in the probe

(CNN) Ahead of a highly anticipated briefing to the full Senate next week by Deputy Attorney General Rod Rosenstein, one Democratic senator says he plans to press him aggressively about the timeline that led to the firing of FBI Director James Comey and whether he plans to call for a special prosecutor to lead an investigation into Russian meddling in the 2016 election and alleged collusion with the Russians by Trump campaign associates.

"I certainly have some very specific questions about the timeline" of Comey's firing, said Michigan Sen. Gary Peters, one of 94 senators who voted to confirm Rosenstein last month. "I hope he realizes the importance of having a special prosecutor."

Prior to Rosenstein's overwhelming confirmation, Senate Minority Leader Chuck Schumer of New York said Rosenstein had assured him he would appoint a special prosecutor if needed.

Asked by CNN's Michael Smerconish if he regretted voting to approve Rosenstein, Peters would say only that he is "not pleased with the actions that we've seen."

In the immediate aftermath of Comey's dismissal Tuesday, White House officials, including Vice President Mike Pence and top aides, stressed that Rosenstein recommended to President Donald Trump that he fire Comey, but Trump in recent days said he would have done so regardless of the recommendation.

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