WASHINGTON —To hear President Trump tell it, his administration is, at any given moment, nearly ideal in its composition and capabilities. It is, as he tweeted in September, a “smooth running machine” — never mind that, prior to the tweet, 15 senior White House and administration officials had quit or been fired and that, in the months since, eight more have joined them.

What makes those departures particularly tricky isn’t just that those who left undercut the idea that the administration hasn’t hit speed bumps. It’s also that, in at least a third of the cases, those who left offered words of disagreement with or criticism of Trump or his administration.

Below is a review of those who left in 2018, the conditions under which they did and what they’ve said about the White House since.

1. Brenda Fitzgerald, director of the U.S. Centers for Disease Control and Prevention. She quit Jan. 31.

Criticisms: None.

2. Rob Porter, staff secretary, was fired Feb. 7.

Criticisms: In Bob Woodward’s book “Fear,” Porter is quoted as saying, “A third of my job was trying to react to some of the really dangerous ideas that he had and try to give him reasons to believe that maybe they weren’t such good ideas.”

3. Hope Hicks, communications director. Quit on Feb. 28.

Criticisms: None. Hicks now works for Fox.

4. Gary Cohn, National Economic Council director. Quit on March 6.

Criticisms: Cohn is also quoted in “Fear.”

“It’s not what we did for the country,” he reportedly said. “It’s what we saved him from doing.” In another anecdote, Cohn is described as removing a document from Trump’s desk to prevent the president from signing it.

5. Rex Tillerson, secretary of State. Fired on March 13.

Criticisms: It was challenging to “go to work for a man who is pretty undisciplined, doesn’t like to read, doesn’t read briefing reports, doesn’t like to get into the details of a lot of things, but rather just kind of says, ‘This is what I believe,’ ” Tillerson said in an interview. He also said Trump had to be told when proposed actions were potentially illegal.

6. Andrew McCabe, deputy FBI director. Fired on March 16.

Criticisms: McCabe called Trump’s attacks on him “unhinged.” Working at the FBI, he said, “is the best job you will ever have. Even if a president decides to attack you and your family.”

7. H.R. McMaster, national security advisor. Fired on March 22.

Criticisms: Prior to leaving the White House, McMaster was reported to have said that Trump was a “dope” who was no smarter than a kindergartner.

8. David Shulkin, secretary of Veterans Affairs. Fired on March 28.

Criticisms: Shulkin says he butted heads with advocates for VA privatization who saw him “as an obstacle to privatization who had to be removed.”

9. Tom Bossert, homeland security advisor. Fired on April 10.

Criticisms: None. He is currently employed by ABC News. It’s not clear whether he signed a nondisclosure agreement when joining the White House.

10. Nadia Schadlow, deputy national security advisor. Quit on April 11.

Criticisms: None. In a lengthy interview with CBS, Schadlow was complimentary about Trump’s involvement in the security team’s processes.

11. Ty Cobb, White House lawyer. Quit on May 2.

Criticisms: “Bob Mueller is an American hero in my view,” Cobb said of the Russia investigation special counsel in an interview in October. “I don’t believe this is a witch hunt.”

12. Joe Hagin, deputy chief of staff. Quit on June 19.

Criticisms: None.

13. Scott Pruitt, Environmental Protection Agency administrator. Quit on July 5.

Criticisms: None. Pruitt’s departure followed a series of questions about his behavior while leading the EPA.

14. Marc Short, legislative affairs director. Quit on July 12.

Criticisms: None. Short is now a CNN contributor. He signed a nondisclosure agreement while working with the Trump campaign, but says he did not sign one at the White House. (The campaign agreement was expansive in its terms.)

15. Donald McGahn, White House counsel. Quit on Aug. 29.

Criticisms: People close to McGahn told CNN that in his last meeting with Trump, the president blamed him for Mueller’s appointment.

16. Jeff Pon, Office of Personnel Management director. Fired on Oct. 5.

Criticisms: None.

17. Nikki Haley, U.N. ambassador. Quit on Oct. 9.

Criticisms: Haley described to NBC News how she leveraged Trump’s personality: “I got the job done by being truthful but also by letting him be unpredictable and not showing our cards.”

18. Jeff Sessions, attorney general. Fired on Nov. 7.

Criticisms: None. Despite ongoing criticism from Trump that ultimately led to his ouster, Sessions told an audience last month that he “enjoy[ed] the honor and appreciate[d] the president allowing [him] to serve almost two years in one of the greatest jobs in the world.”

19. Mira Ricardel, deputy national security advisor. Fired on Nov. 14.

Criticisms: None.

20. John F. Kelly, chief of staff. Fired on Dec. 8.

Criticisms: Working as chief of staff was a “bone-crushing hard job,” Kelly said in an interview with the Los Angeles Times. He said Trump never asked him to do anything illegal “because we wouldn’t have.”

21. Nick Ayers, Vice President Mike Pence’s chief of staff. Quit on Dec. 9.

Criticisms: None. Ayers did, however, decline to step up as Trump’s chief of staff, a job the president had made very clear he hoped Ayers would accept.

22. Ryan Zinke, secretary of the Interior. Quit on Dec. 15.

Criticisms: None.

23. James N. Mattis, secretary of Defense. Announced his resignation Dec. 20.

Criticisms: “Our strength as a nation is inextricably linked to the strength of our unique and comprehensive system of alliances and partnerships,” he wrote in his resignation letter. “My views on treating allies with respect and also being clear-eyed about both malign actors and strategic competitors are strongly held and informed by over four decades of immersion in these issues,” he added, remarking that he was leaving because Trump had “the right to have a Secretary of Defense whose views are better aligned with [his] on these and other subjects.”

Bump writes for the Washington Post.