Controversial Trump national security aide to leave White House, official says Sebastian Gorka is reportedly leaving his position at the White House.

 -- Sebastian Gorka, a top national security adviser to President Donald Trump who has come under scrutiny over alleged ties to a Nazi-aligned group in Hungary, is expected to leave his position at the White House, a senior administration official said Sunday.

The official said the departure would not be immediate and did not offer details on where Gorka, a member of the White House's Strategic Initiatives Group, would head next.

In March, three Democratic U.S. senators wrote a letter asking questions about Gorka's alleged ties to Vitezi Rend, a right-wing nationalist group in Hungary that some associate with Nazi collaboration. Last month Democratic House members called for his resignation over his alleged ties to anti-Semitic groups.

Gorka has denied the allegations.

The Strategic Initiatives Group is an advisory panel that was created by Trump's chief strategist, Steve Bannon, to run parallel to the National Security Council but fizzled out during the early days of the administration, according to an Associated Press report.

Reached by phone, Gorka did not deny that he was departing, but he declined to offer a comment. The White House also declined to comment on the matter.

After the exit of former national security adviser Michael Flynn, Gorka became one of the most controversial members of the administration as reports surfaced alleging links to Vitezi Rend, which the U.S. State Department lists as being "under the direction of the Nazi government of Germany" during World War II — which The Forward, an American Jewish news outlet, reported in March.

Rep. Jerrold Nadler, D-N.Y., cited The Forward's report in a letter addressed to Trump in March, asking the White House to "immediately clarify" whether Gorka was a member.

"If Sebastian Gorka is indeed a member of this organization, as high-ranking leaders of the organization claim he is, he would have been required to disclose this information on his immigration application and on his application to be a naturalized U.S. citizen," Nadler stated in the letter.

"Therefore, I am asking that you provide the House Committee on the Judiciary with Sebastian Gorka's immigration application and his application to be a U.S. citizen, so that the committee can be assured that he did not enter this country under false pretenses," he continued.

Gorka, a former Breitbart editor who holds a Ph.D. in political science, dismissed The Forward's claims in a statement to ABC News in March.

"I've been a committed opponent of anti-Semitism, racism and totalitarianism all my life," he said. "Any suggestion otherwise is false and outrageous."