Sebastian Gorka. Facebook Sebastian Gorka, the Breitbart national security editor and a Fox News contributor, is expected to join President Donald Trump's White House, a source familiar with the matter told Business Insider.

The source said that the position is likely in the National Security Council. A Fox News spokesperson said the network terminated Gorka's contributor agreement when he informed executives of his new position.

Gorka, who has written stories for Breitbart since early 2014, was a founding member of the Council for Emerging National Security Affairs and has been awarded the Joint Civilian Service Commendation, according to a bio on his website. (He recently made his website private.) The national-security analyst is the author of "Defeating Jihad," a New York Times best-seller.

He was also the vice president for counterterrorism and irregular warfare at the Threat Knowledge Group, and he said in a July Breitbart story that he had written policy papers for Trump. He was paid by the campaign for policy consulting, according to Federal Election Commission filings.

Gorka's expected move to the National Security Council further represents Breitbart's expanding role inside the Trump White House.

The website's chairman, Stephen Bannon, served as Trump's campaign CEO and now works as White House chief strategist. On Sunday, it was reported that Julia Hahn, a hardline immigration writer for Breitbart, was also expected to join the Trump White House as a special assistant to the president.

Neither Gorka nor the White House responded to multiple requests for comment. A spokesperson for Breitbart was also not immediately available for comment on Tuesday morning.