WASHINGTON — Two members of congress, a cabinet official, a presidential confidant and a frequent guest on Fox News are among those being considered by President Donald Trump to be the next attorney general, multiple sources tell NBC News.

One of those, former New Jersey Governor Chris Christie, was a close adviser to the president in his 2016 presidential campaign. He has been largely sidelined by the administration since then but resurfaced at the White House on Thursday for what White House officials said was for a previously scheduled meeting on prison reform.

Rep. John Ratcliffe, R-Texas, and retiring Rep. Trey Gowdy of South Carolina, have also joined the list of those in the running, the sources say.

Ratcliffe, a former political appointee of President George W. Bush who was later appointed to be U.S. Attorney of the Eastern District of Texas, has become a top candidate.

He was elected to Congress in 2014 and has been named as the most conservative Texas legislator by the Heritage Foundation. He made a name for himself when he grilled former FBI agent Peter Strzok in a House Judiciary Committee hearing about text messages he sent ahead of the 2016 election.

Gowdy, who led the House investigation into former Secretary of State Hillary Clinton's handling of the attack that led to the deaths of four Americans in Benghazi, is retiring from Congress at the end of the year and was a prosecutor before coming to Congress. He and Trump have had a contentious relationship, especially since Gowdy voted “present” on a House bill to keep the House’s Russia investigation going when every other Republican voted “no.”

Neither Ratcliffe nor Gowdy’s office responded to requests for comment.

Sen. Lindsey Graham, R-S.C., who is close to Gowdy, has become an adviser to the president on the position. Frequently mentioned for the job himself, Graham has said repeatedly that he is not interested. But anticipating that Sessions would be fired or would resign, he has been working on a list of potential replacements to present to the president.

And Graham, who could be the next chairman of the Senate Judiciary Committee, could have a large say on if the nominee is successful in the Senate.

Graham said he discussed Sessions’ successor with the president at the White House on Thursday. “I’m confident the White House is looking for someone who the President and country can have confidence in, and be confirmed by the Senate,” Graham said in a statement.

Other names that have been discussed include Noel Francisco, the current solicitor general of the United States, who was appointed by Trump last year. Trump’s Health and Human Services secretary Alex Azar is also a contender, sources tell NBC News.

Azar's spokeswoman, Caitlin Oakley said the secretary is happy in his current job. "Secretary Azar has repeatedly said that this is the best job he has ever had and that this is his dream job. He plans to continue serving President Trump as his HHS Secretary."

Andrew McCarthy, a former assistant U.S. attorney for the Southern District of new York and current columnist for the National Review, is also said to be under consideration. McCarthy is a common guest on Fox News, which Trump appreciates in an official.

McCarthy has also written that acting Attorney General Matthew Whitaker could be amidst an “audition” for the permanent gig. Whitaker, Sessions former chief of staff, has spoken negatively about the Russia probe when he was an analyst on CNN.

But Whitaker’s appointment is unlikely, unless he is removed from the acting position. Under the Federal Vacancies Reform Act, a person appointed to the position of Acting Attorney General who has not previously been confirmed by the Senate must step out of the acting position in order to be confirmed on a permanent basis.

Finally, losing Kansas gubernatorial candidate Kris Kobach has been mentioned as well. Kobach, a former Kansas secretary of state and member of Trump’s transition team who led a failed advisory board to investigate voter fraud, has also made a name for himself on hard right immigration policies. But most observers say it would be quite difficult for Kobach to ever be confirmed by the Senate because of his controversial positions on hot button issues.

Getting passed the Senate will be a key requirement for any nominee. At least three Republicans have already said that protecting the Mueller investigation is a critical concern.

Sen. Susan Collins of Maine said the Mueller probe “must be allowed” to continue. Senator-elect Mitt Romney tweeted “it is imperative” the probe continues, and Sen. Thom Tillis of North Carolina said it will “undoubtedly be an important issue during the confirmation.”