"There's no there, there." That's how Commerce Secretary Wilbur Ross described the FBI's investigation into possible Trump campaign ties to Russia.

In a rare response from a Trump Cabinet member, Ross told CNBC's "Squawk Box" on Thursday the inquiry is a "sideshow." He added, "This is all rumor. It's all innuendo."

Reacting to the appointment of former FBI Director Bob Mueller as special counsel to oversee the agency's Russian investigation, Ross said he hopes Mueller "brings the matter to a head," so the media can "go on to something else."

President Donald Trump reacted to the appointment of Mueller in tweets Thursday morning.

"With all of the illegal acts that took place in the Clinton campaign & Obama Administration, there was never a special councel appointed!"

This is the single greatest witch hunt of a politician in American history!

But in testimony before the Senate Intelligence Committee last week, acting FBI Director Andrew McCabe said of the Russian probe, "We consider it to be a highly significant investigation."

Commerce Secretary Ross, a billionaire who made his fortune investing in distressed assets, said the investigation is a distraction, but the president is still running the country effectively.

Ross said he sees "no reason" for the notion that the GOP policy agenda including tax cuts would be delayed.