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.
The sources emphasized that investigators remain keenly interested in people who previously wielded influence in the Trump campaign and administration but are no longer part of it, including former national security adviser Michael Flynn and former campaign chairman Paul Manafort.
Flynn resigned in February after disclosures that he had lied to administration officials about his contacts with Russian ambassador Sergey Kislyak. Current administration officials who have acknowledged contacts with Russian officials include Trump son-in-law Jared Kushner, as well as Cabinet members Attorney General Jeff Sessions and Secretary of State Rex Tillerson.
People familiar with the investigation said the intensifying effort does not mean criminal charges are near, or that any such charges will result. Earlier this week, Deputy Attorney General Rod Rosenstein appointed former FBI Director Robert Mueller to serve as special counsel and lead the investigation into Russian meddling.
It is unclear exactly how Mueller's leadership will affect the direction of the probe, and he is already bringing in new people to work on the team. Those familiar with the case said its significance had increased before Mueller's appointment.
While the case began quietly last July as an effort to determine whether any Trump associates coordinated with Russian operatives to meddle in the presidential election campaign, the investigative work now being done by the FBI also includes determining whether any financial crimes were committed by people close to the president. The people familiar with the matter said the probe has sharpened into something more fraught for the White House, the FBI and the Justice Department - particularly because of the public steps investigators know they now need to take, the people said.
When subpoenas are issued or interviews are requested, it is possible the people being asked to talk or provide documents will reveal publicly what they were asked about.
A small group of lawmakers known as the Gang of Eight were notified of the change in tempo and focus in the investigation at a classified briefing on Wednesday evening, the people familiar with the matter said. FBI Director James Comey had publicly confirmed the existence of the investigation in March.
Justice Department spokeswoman Sarah Isgur Flores said, "I can't confirm or deny the existence or non-existence of investigations or targets of investigations." An FBI spokesman declined to comment.
White House spokesman Sean Spicer said, "as the president has stated before, a thorough investigation will confirm that there was no collusion between the campaign and any foreign entity.''