Washington (CNN) The White House is currently discussing potential candidates to replace John Bolton as national security adviser after he was ousted Tuesday, with at least 10 names being circulated at this time, several sources told CNN.

While President Donald Trump said he would make a decision "next week," there does not appear to be a short list at the moment. White House deputy press secretary Hogan Gidley told reporters Tuesday that Charles Kupperman, who was Bolton's deputy, will serve as acting national security adviser until a replacement is picked.

Given Trump's unpredictable nature, sources warn that the President could choose someone who is not being discussed right now to become his fourth national security adviser in less than three years.

But in the short term, these are the individuals who have been mentioned as possible candidates:

Brian Hook, US Special Representative for Iran and senior policy adviser to Mike Pompeo

Hook's name is being floated as a possibility to replace Bolton, according to three sources familiar with the discussions.

He is interested in and campaigning for the job in the sense that it is clear, to both the White House and other government officials, that he'd be interested in the role, according to one source familiar with the process.

Hook started at the State Department under Secretary Rex Tillerson and remained a key member of the team when Pompeo took over. He recently traveled with Trump's senior adviser and son-in-law, Jared Kushner to the Middle East trip and is well liked at the White House, another source told CNN. Hook was tapped by Pompeo to lead the State Department's efforts on Iran.

Ricky Waddell, Major General in the United States Army Reserve who served for a year as Trump's Deputy National Security Adviser to Trump

White House officials are discussing Waddell as an option to replace Bolton as well, according to three sources familiar with the ongoing talks. Waddell left the administration last year and he was close with Trump's former Chief of Staff John Kelly.

Steve Biegun, US Special Representative to North Korea

Biegun's name is also circulating among White House officials, according to three sources familiar with the discussions. Biegun, who is also under consideration to be the next Deputy Secretary of State, has a good relationship with Pompeo and is known to have impressed Trump during their conversations about North Korea and given his background as an executive at Ford Motors, a source says.

Rob Blair, national security adviser to acting chief of staff Mick Mulvaney

Blair, was recruited by acting Chief of Staff Mick Mulvaney from the Office of Management and Budget in January. His hiring allowed Mulvaney to have a hand in national security issues without having to go through Bolton. One administration official said that Blair could be a favorite because of his support from Mulvaney.

Richard Grenell, US ambassador to Germany

Grenell is also interested in the job and has been campaigning for the role, a source familiar with the process said. Grenell is an ally of Bolton which could be a barrier to entry but he is viewed as an effective ambassador by the White House, one source says.

Pete Hoekstra, US ambassador to the Netherlands

Hoekstra's name was floated as a potential replacement for Bolton by a Trump ally. The ambassador has also come up in discussions for the Director of National Intelligence vacancy. Hoekstra spent seven years on the House Intelligence Committee and is regarded by lawmakers on both sides of the aisle as an experienced official. When Trump was asked about him last month, he said "I like Pete Hoekstra a lot. He's great. He's doing a fantastic job in the Netherlands right now."

Keith Kellogg, national security adviser to Vice President Mike Pence

Kellogg is a retired Army Lieutenant General who previously served on Trump's NSC under Bolton's predecessor, H.R. McMaster. His name has also been mentioned during internal White House discussions as a possible candidate to fill the role vacated by Bolton.

Douglas Macgregor, retired US Army Colonel

Macgregor appears often on Fox News to discuss national security issues. He has recently been publicly urging Trump to pull out of Afghanistan. His name has been discussed, according to one source.

Jack Keane, retired four-star general

Keane has informally advised the President on matters of national security, including negotiations with the Taliban. But while his name has surfaced in discussions among White House officials, a source familiar with Keane's thinking told CNN he would not accept the job if asked, and doesn't expect to be offered the post after turning down the Secretary of Defense job twice.

Fred Fleitz, former chief of staff to Bolton at NSC

Fleitz has also surfaced as a possibility, according to three sources familiar with the discussions. He tweeted a picture of himself with the President in the Oval Office Tuesday shortly before Bolton's departure was announced. Fleitz, who is known to have a close relationship with Bolton, which could cut him from the short list, declined to comment when reached by phone. CNN previously reported that Fleitz had been an early contender for the DNI role but was viewed as unconfirmable.

CLARIFICATION: This article has been updated to add more precise detail from a source familiar with the process on Brian Hook's interest in succeeding Bolton.