Deputy FBI Director Andrew McCabe has reportedly told top officials at the bureau that they could be called to testify in an investigation into whether President Trump obstructed justice.

According to Vox, McCabe has told colleagues he himself could be a a witness in the investigation into whether Trump obstructed the FBI's investigation into potential ties between Trump campaign staff members and Russia. The Russia investigation is now being led by special counsel Robert Mueller.

"What you are going to have is the potential for a powerful obstruction case," a senior law enforcement official told Vox.

The official said several people in the upper reaches of the FBI can vouch for former FBI Director James Comey's allegations that the president sought to interfere in the Russia investigation.

"This has never been the word of Trump against what [James Comey] has had to say. This is more like the Federal Bureau of Investigation versus Donald Trump," the official told Vox.

Potential witnesses at the FBI include the FBI's general counsel, James Baker, as well as Comey's former chief of staff, associate deputy director David Bowdich, and executive assistant director of the National Security Branch Carl Ghattas.

Officials think Attorney General Jeff Sessions and Deputy Attorney General Rod Rosenstein could also be possible fact witnesses in the investigation into whether Trump obstructed justice, according to Vox.