President Trump, Vice President Pence, First Lady welcome American returnees home

"Our administration has been fully cooperating with the Special Counsel-" Pence started.

Pence spoke at Joint Base Andrews with several media outlets ahead of the return of three Americans who had been detained by North Korea.

MITCHELL: Do you think his investigation is a hoax?

He continued: "Nor any mention, by Vice President Pence, of the five guilty pleas, one person sentenced, 23 defendants and 75 criminal charges in all Robert Mueller's investigation has yielded so far".

Pence raised almost $1.2 million for his campaign thanks largely to the support of his brother, pro-Trump groups and top Republicans. "And I would respectfully encourage the special counsel and his team to bring their work to completion".

"What I can say is that that private matter is something that I don't have any knowledge about", Pence told NBC. The president has repeatedly blasted the inquiry and members of Mueller's team for being either biased Democrats or members of the so-called "deep state" conspiring against him and his administration.

More: Can Robert Mueller subpoena Donald Trump?

Mueller is probing whether any Trump associates colluded with Russian Federation during the 2016 campaign, among other issues involving the president's aides.

The adult film actress, whose stage name is Stormy Daniels, says she had a torrid affair with Trump in 2006 and 2007, just after future first lady Melania Trump gave birth to their son Barron.