The Washington Post reported today,

The law enforcement investigation into possible coordination between Russia and the Trump campaign has identified a current White House official as a significant person of interest, showing that the probe is reaching into the highest levels of government, according to people familiar with the matter.

The senior White House adviser under scrutiny by investigators is someone close to the president, according to these people, who would not further identify the official.

The revelation comes as the investigation also appears to be entering a more overtly active phase, with investigators shifting from work that has remained largely hidden from the public to conducting interviews and using a grand jury to issue subpoenas. The intensity of the probe is expected to accelerate in the coming weeks, the people said.