Investigators examine Kushner's meeting with Russian banker

In talks with Kislyak in December, Kushner floated the possibility of setting up a secure line of communication between the Trump transition team and Russia - and having those talks take place in Russian diplomatic facilities in the USA, essentially concealing their interactions from U.S. government scrutiny.

A Republican consultant, Dubke joined the White House team in February.

Hope Hicks, director of strategic communications in the White House, provided a statement to CBS News.

Kellyanne Conway, White House counselor, has told The Associated Press that Dubke handed in his resignation before President Donald Trump left for his worldwide trip earlier this month.

For example, Trump has entertained bringing his former campaign manager, Corey Lewandowski, and former deputy campaign manager, David Bossie, more formally back into the fold.

President Donald Trump says Russian officials "must be laughing at the U.S".

Until Saturday, President Trump's son in law, Jared Kushner was going to be a witness in the ongoing FBI investigation in the relation between the campaign and Russian Federation. Both Lewandowski and Bossie discussed the prospect with the president before his trip, according to one person told of the conversations.

Kushner's involvement in the proposed back channel was first reported by The Washington Post, which said he suggested using Russian diplomatic facilities for the discussions, apparently to make them more hard to monitor.

The back channel was meant to connect Michael Flynn, who later became Trump's first national security adviser, with Russian military leaders, said the person, who wasn't authorized to publicly discuss private policy considerations and spoke on condition of anonymity. His last day has not yet been determined.

A senior administration official said Kushner was keeping his head down and focusing on work after the foreign trip.

"Mike will assist with the transition and be a strong advocate for the president and the president's policies moving forward", Priebus said.

"If you're going to create a back channel that relies exclusively on the Russian communications and apparatus, that's a really serious issue", added Mark Lowenthal, a former Central Intelligence Agency assistant director. Just back from his nine-day trip to the Middle East and Europe, Trump dismissed recent reports as "fake news". The New York Times also confirmed the story from three independent sources. "In getting his security clearance, you're supposed to list those, and then there's this peculiar one where he is trying to set up a thing within the Russian communications system so that our own intelligence couldn't be part of it, which is very unusual".

"There are so many "facts" in the public domain now that many people are connecting them in a way that has them concluding the Trump campaign must have been guilty of conspiring with the Russians in a way that would be a violation of the law".