National security adviser Mike Waltz is out, with Secretary of State Marco Rubio replacing him on an interim basis.

On Thursday afternoon, President Trump announced that Waltz, a former GOP member of the House, would now be his nominee for U.S. ambassador to the United Nations.

“Having served in uniform on the battlefield, in Congress, and as my National Security Advisor, Mike Waltz has consistently prioritized our Nation’s Interests. I am confident he will continue to do so in this new position,” Trump stated in a Thursday post on Truth Social.

Waltz’s deputy, Alex Wong, is also expected to leave. Both have been the focus of criticism from far-right figures within the MAGA movement, and Waltz was a key figure in the Signal scandal that brought embarrassment to the Trump administration in March.

Here are the leading candidates to replace Waltz in a permanent capacity.

Marco Rubio

The U.S.’s top diplomat could see his interim dual role extended to a permanently expanded portfolio.

Rubio will be the first to serve as both the secretary of State and national security adviser concurrently since the late Henry Kissinger. 

State Department spokesperson Tammy Bruce, who learned of Rubio’s new role during her press briefing Thursday, said he has “worn several hats” during Trump’s second term and expressed confidence that he can carry the additional load.  

Rubio has been involved in the administration’s push to forge a peace agreement that would end the Russia-Ukraine war, and he has been a central figure in attempts to deport foreign students involved in anti-Israel protests.

Steve Witkoff

Steve Witkoff is a leading candidate to replace Waltz, according to multiple outlets, having quickly accumulated a sprawling portfolio as Trump’s favored international negotiator.

The Hill has reached out to Witkoff’s spokesperson for comment. 

Witkoff, a billionaire real-estate investor, was tapped by Trump to be his special envoy to the Middle East. He has since become the point person for talks with Russian President Vladimir Putin over the war in Ukraine and has been the lead negotiator in early talks with Iran over its nuclear program.

Witkoff’s relationship with Trump goes back decades. However, he would be a highly unusual pick as national security adviser, with no official experience in government, foreign affairs or the military.

Ric Grenell

Ric Grenell is serving as Trump’s envoy for special missions and was seen as a candidate for both national security adviser and secretary of State heading into Trump’s second term. He is also interim executive director of the Kennedy Center. 

Grenell has kept a relatively low profile in recent months, but he was involved in the release of six Americans held hostage in Venezuela in January.

Grenell served in multiple posts during Trump’s first four years in the White House, including acting director of national intelligence and ambassador to Germany. Trump also tapped Grenell to be his special envoy for Serbia and Kosovo during his first Oval Office stint. 

Stephen Miller

Axios reported Friday that Stephen Miller, Trump’s top domestic policy adviser, is “gathering buzz” in Washington amid the search for Waltz’s replacement. 

Miller has been a leading force in Trump’s immigration crackdown, as the president’s homeland security adviser, and is often a public face of the administration’s most divisive deportation actions. 

A move to the national security brief would mark a significant shift of Miller’s attention within Trump’s inner circle. 

Miller was part of a Signal group that accidentally included journalist Jeffrey Goldberg. In that discussion, he effectively shut down debate among top officials over Trump’s plans to attack Houthi rebels threatening Red Sea shipping lanes. 

Michael Anton

Michael Anton has quickly become a favorite candidate to replace Waltz in online MAGA circles, as Politico reported. He was also appointed last week to lead technical talks with Iran over its nuclear program.

He is the State Department’s policy planning director and was in the Vatican last weekend when Trump met with Ukrainian President Volodymyr Zelensky.

During Trump’s first White House term, Anton served on the National Security Council. He later worked as a senior fellow at the Claremont Institute. 

Sebastian Gorka

Sebastian Gorka, who is a first Trump administration alumnus, could also be in the mix. 

He was tapped in November last year to be the deputy assistant to the president and the senior director for counterterrorism. 

“Since 2015, Dr. Gorka has been a tireless advocate for the America First Agenda and the MAGA Movement, serving previously as Strategist to the President in the first Trump Administration,” Trump said about Gorka at the time.

Trump picked Gorka to be on his national security advisory board in July 2020. Before that role, he was advising the administration on counterterrorism matters.

Robert O’Brien

Robert O’Brien was Trump’s fourth and final national security adviser during his first term, serving from 2019 to 2021. He was seen as a contender for secretary of State before Rubio’s nomination.

O’Brien was Trump’s special envoy for hostage negotiations before becoming national security adviser. He previously advised high-profile Republicans, including former Sen. Mitt Romney (Utah) and Sen. Ted Cruz (Texas).

He was also a relatively rare figure in the first Trump administration, acknowledging Joe Biden’s victory in the 2020 election and promising an orderly transition. O’Brien was interviewed by the House committee that investigated the Jan. 6, 2021, attack.

Fred Fleitz

Fred Fleitz was chief of staff and executive secretary of the National Security Council for a few months during the first Trump administration, from May to October in 2018. He was a longtime top aide to John Bolton, Trump’s national security adviser at the time.

He is currently vice chair of the America First Policy Institute Center for American Security and a Newsmax contributor.

Fleitz spent nearly three decades in various national security positions, including in the CIA, the State Department and as a House Intelligence Committee staff member. 

He was on Trump’s shortlist of candidates to replace Bolton in 2019, a list that also included O’Brien, Lisa Gordon-Hagerty, Keith Kellogg and Ricky Waddell.

Keith Kellogg

Retired Lt. Gen. Keith Kellogg was initially appointed as Trump’s special envoy to the Russia-Ukraine talks in January, but he saw that role scaled back to focus on the Ukraine side of talks, which includes coordination with Europe. Witkoff has handled the Russia side of the brief.

Kellogg served as national security adviser to then-Vice President Mike Pence in the first Trump administration and as chief of staff for the National Security Council.

Kellogg is a decorated veteran of both the wars in Vietnam and the Persian Gulf, and he was a senior Pentagon official during the Sept. 11 terrorist attacks.

The retired general briefly served as acting national security adviser following the resignation of Michael Flynn, also a retired lieutenant general, in 2017.

Christopher Landau

Another option to succeed Waltz is Deputy Secretary of State Christopher Landau, Reuters reported, citing an unnamed source. 

The State Department declined to comment on the possibility and referred The Hill to the White House. 

Landau, an attorney, was Trump’s ambassador to Mexico from 2019 to 2021. 

Before his time in Mexico City, Landau practiced law in Washington, D.C., for more than three decades.

Elise Stefanik

Rep. Elise Stefanik (R-N.Y.) would be a top contender — if it weren’t for the House Republican math problem.

Stefanik was Trump’s nominee to be the next United Nations ambassador, until she was pulled in March over GOP jitters over its paper-thin majority in the House and potentially losing her usually safe seat in upstate New York.

So while now may not be her time for the Trump administration, she’ll likely be back in the mix for Cabinet posts if Trump shakes up his team after the midterms.