Tim Morrison, a National Security Council official and a key witness in the House’s impeachment inquiry, is expected to leave his job, an administration official confirmed to TPM Wednesday.

It’s not clear if Morrison is resigning or being fired. NPR first reported the news Wednesday.

An administration official told TPM in an email: “After more than a year of service at the National Security Council, Mr. Morrison has decided to pursue other opportunities – and has been considering doing so for some time. We wish him well.”

Morrison is scheduled to testify in the impeachment probe on Thursday and will appear if subpoenaed, his lawyer told TPM last week.

The senior director for European and Russian affairs on the National Security Council, Morrison took that position after Fiona Hill announced her resignation from the NSC in July.

Both officials witnessed first hand several of the incidents now under scrutiny in the impeachment probe.

This post has been updated.