Senate Majority Leader Mitch McConnell tells us not to worry our pretty little heads about the need for a Special Prosecutor because:

Installing a special prosecutor to take over the FBI’s probe of whether Trump campaign figures were working with Russian interests before the election would “only serve to impede the current work being done” by the Senate Intelligence Committee, which is conducting an investigation, McConnell said.

Also in the  SFgate article was a quote from Dianne Feinstein:

“I can’t go into the specifics, but you and I know that it was rather comprehensive for this kind of briefing. The FBI director was precise and he presented us with substantial information. It was clear the FBI was taking its job seriously and that a substantial investigation was under way.”