Another high-ranking member of President Donald Trump’s National Security Council is stepping down from their post as John Bolton, the president’s new national security adviser, moulds his team.

Nadia Schadlow resigned from her post in a letter Tuesday, and will officially leave her post April 27.

Ms Schadlow, a deputy national security adviser for strategy, was close with ex-National Security Adviser HR McMaster, who was responsible for Mr Trump’s first National Security strategy. She is the third senior national security adviser to resign or be pushed out since Mr Bolton was announced as Mr McMaster’s replacement.

White House spokesman Raj Shah told media that the Trump administration thanks Ms Schadlow for “her service and leadership” and that “we wish Nadia, and her family, the best.”

“The administration thanks Dr Schadlow for her service and leadership in crafting the President’s ‘America First’ national security strategy,” Mr Shah’s statement reads. “The strategy has set a strong foundation going forward for protecting the homeland, promoting American prosperity, preserving peace through strength and advancing American influence. We wish Nadia and her family the best.”

Ms Schadlow is the latest in a series of high-level staffers who have chosen to leave, or who have been pushed out since Mr Bolton was appointed to his position. Their ranks include spokesman Michael Anton, and Homeland security Adviser Tom Bossert. Sources close to the National Security Council told reporters at CNN that they had expected Ms Schadlow’s departure from the group for months.

Mr Bolton officially joined the White House operations Monday.

In Ms Schadlow’s resignation letter, the outgoing deputy said that she is proud of her time serving Mr Trump.

“Together, we captured your vision for a strong and confident America and developed your America First National Security Strategy — which turned that vision into a strategic direction for your administration,” her letter read. “And I am particularly proud that you were able to submit your NSS to Congress earlier than any previous administration … on time and under budget!”

Ms Schadlow’s resignation is likely to raise some alarms in Washington, where she has been regarded as one of the few reliably steady hands in the Trump White House when it comes to national security concerns.

More resignations are expected as Mr Bolton continues to review the resumes of top staffers serving on the National Security Council, sources have told multiple news outlets.