FBI Deputy Director Andrew McCabe expected to retire as pressure mounts

— -- Embattled FBI Deputy Director Andrew McCabe is expected to retire from the FBI in several months when he becomes eligible to receive retirement benefits, a source familiar with the matter tells ABC News.

McCabe has come under fire from President Trump and congressional Republicans who have expressed concerned about political bias at the Department of Justice and FBI. McCabe was grilled twice this week on Capitol Hill by members of the House Intelligence, Judiciary and Oversight Committees behind closed doors – meetings described to ABC News by participants as contentious.

President Trump took to Twitter to attack McCabe and react to reports of his retirement Saturday after a golf outing in Florida, where he is vacationing with his family at his Mar-a-Lago club in Palm Beach.

Republicans have raised concerns about McCabe because of his wife’s 2015 Virginia Senate campaign, which received contributions from a political group associated with Virginia Gov. Terry McAuliffe.

After the firing of James Comey in May, many FBI insiders had expected McCabe - a deputy director for roughly two years who supervised the Clinton email investigation and filled in for Comey after his firing - to move on from his position with the appointment of new FBI Director Christopher Wray. His retirement is not viewed as premature by some in the bureau, or seen as having any connection to Trump’s attacks against him.

Trump’s tweets have prompted new outpourings of support for the bureau’s agents. Close Comey associate and Brookings Institution fellow Ben Wittes tweeted Saturday that he had donated $1,000 to the FBI Agents Associated in light of Trump’s attacks.

Others have since followed suit.