Current White House staffer caught up in Russia probe, source says Officials would not identify the staffer.

 -- The federal investigation of alleged collusion between associates of President Donald Trump and Russian officials is looking not only into Trump campaign advisers previously cited in public accounts, but it is also scrutinizing at least one current White House staffer, a source familiar with the matter told ABC News.

The Washington Post was the first to report on this detail of the investigation, saying a "senior White House adviser" has become "a significant person of interest" in the probe.

Officials speaking to ABC News would not identify the staffer, and it is unclear exactly why authorities are interested in this individual.

The Department of Justice appointed a special counsel to spearhead the investigation into Russian meddling in the 2016 presidential election -- as well as possible collusion between the Trump campaign and Russian officials. Trump has repeatedly dismissed the Russia storyline as "fake news."

Multiple Congressional committees are also investigating potential ties between the President’s campaign and the Russians.

White House Press Secretary Sean Spicer provided a statement responding to The Washington Post denying collusion.

"As the President has stated before - a thorough investigation will confirm that there was no collusion between the campaign and any foreign entity," said Spicer.