"Presidential candidates do not have emails chains with foreign governments who are talking about how they can elect you and have dirt on your opponent," Sanders said. "That is a clear violation of campaign finance law."
"It is not true that this is politics as usual," Sanders continued. "This is very, very unusual. And that is why these investigations are taking place."
Sanders did not say mounting evidence in the Russia probe showed a smoking gun, but that there is "very strong evidence about the possibility of collusion."
He said focus should be placed on Americans' trust in the investigation.
"What is important is that every American, whether they're conservative or progressive, you like Trump, you don't like Trump — that they believe this process is objective and it is fair. That it is methodical," Sanders said.
"Let the process continue," Sanders continued. "We'll reach judgment after the evidence is accumulated."