WATCH: Ex-Trump aide Jason Miller goes down in flames trying to dismiss Russian hacking links to White House

On Friday, Jason Miller, a former campaign adviser to President Donald Trump, struggled to defend President Trump's summit with Vladimir Putin during an interview with CNN's Anderson Cooper.

"Jason, 12 Russian intelligence officials are charged with hacking into Democratic systems and state voting data, and yet he stood there today on live international television and called the investigation a witch-hunt. Is that appropriate?" Cooper asked.

"I think there are a couple of different things that are going on here. First, we're not talking about the witch-hunt, we're talking about this continued allegations that there is some sort of coordination between the campaign and a foreign entity, which I think the president is spot-on." Miller said.

However, before he could finish his thought, Cooper fact-checked him. "No, no. He is calling the witch-hunt the Mueller investigation. The whole  Mueller investigation is a witch-hunt. And the Mueller investigation is more than just looking into any possible Trump involvement," Cooper said.

Miller tried to defend himself by calling the investigation a "deep state fishing expedition."

Cooper would not let him off the hook.

"You're saying it's a deep state fishing expedition? He is calling an attack on the United States, a witch-hunt. I mean, that's what you just validated," Cooper said.

Cooper continued to grill him on his weak defense.

“So you think it’s unfair that they have indicted these Russian intelligence agents for this attack? You think that’s an unfair aspect, that it’s part of a fishing expedition? That they’re off the reservation? That it’s not part of the program?" the CNN host pressed.

"You just said the Mueller investigation has gone off the reservation," Cooper said. "Where they're at right now is indictments of Russians for cyber-attacking the United States. That's not a good thing. That’s an inappropriate use of the Mueller investigation -- is what you’re saying?" Cooper said.

Miller continued to go down in flames. "I think when this investigation was started the allegations were that there was some sort of coordination between the campaign and a foreign entity. Clearly as they're starting to look nothing has been proven in any way, shape or form that the campaign coordinated with a foreign entity to impact the election." he said.

"So they should stop now is what you're saying?" Cooper concluded.

Watch below.