Rosenstein, who made the decision to appoint former FBI Director Robert Mueller as a special counsel for that matter, was also asked whether Mueller's relationship with Comey made Mueller a less than ideal choice.

"I made the decision to appoint Director Mueller based upon his reputation. He had an excellent reputation. Really bi-partisan support for his integrity. That's why I made that decision....But, I can assure you that if there were conflicts that arose, because of Director Mueller or anybody employed by Director Mueller, we have a process within the department to take care of that," Rosenstein said.

Trump said last month he found that connection "bothersome." He also expressed concern that some attorneys hired by Mueller either > supported Democratic presidential nominee Hillary Clinton or worked for her.

Asked about some prosecutors having donated to Clinton's campaign, Rosenstein suggested that the public should focus on the outcome of the investigation and not the background of those conducting it.