Former chief White House counselor Steve Bannon and onetime Donald Trump campaign manager Corey Lewandowski have received letters requesting they testify before the House Intelligence Committee in January.

Bannon, who left the White House in August, is the executive chairman of Breitbart News, the far-right, nationalist publication that helped elevate Trump to the White House. The former top aide reportedly blames Trump’s son-in-law Jared Kushner for the president’s Russia problems, which includes a special counsel investigation and multiple Congressional probes.

Lewandowski served as Trump’s campaign manager from January 2015 to June 2016. He left after sparring with Paul Manafort, who became campaign chairman following Lewandowski’s departure. Manafort was indicted in October on a litany of charges as part of special counsel Robert Mueller’s investigation.

The House intelligence committee’s investigation has been mired by infighting in recent months as Republicans try to refocus the probe away from Russian collusion and toward a perceived bias within the FBI. Committee chairman Rep. Devin Nunes (R-CA) is reportedly leading a small group of Republicans to build a case against senior officials at the FBI and Department of Justice.