Ret. Army Gen. Jack Keane, a former Army vice chief of staff, is an outspoken defense hawk who appears frequently on Fox News. | Alex Wong/Getty Images Defense Who might replace Mattis?

Defense Secretary Jim Mattis' resignation amid deep policy disagreements with President Donald Trump raises the question of who might replace him — and perhaps more importantly, who would want the job.

Mattis was one of the few Trump administration officials to still enjoy bipartisan support on Capitol Hill, and lawmakers and allies abroad saw him as a steadying presence in a chaotic administration. It's unclear if his replacement will enjoy that same support in Congress and around the world.


Here are a few people whose names have come up as potential Mattis replacements — as well as the drawbacks they would face:



Retired Army Gen. Jack Keane



Keane, a former Army vice chief of staff, is an outspoken defense hawk who appears frequently on Fox News as a national security analyst. A hard-nosed national security hand with the military background often valued by Trump, Keane's name has been floated frequently as a Mattis replacement.

Morning Defense newsletter Sign up for Morning Defense, a daily briefing on Washington's national security apparatus. Email Sign Up By signing up you agree to receive email newsletters or alerts from POLITICO. You can unsubscribe at any time. This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

As Trump contemplated trimming his planned defense budget request to $700 billion just weeks ago, Keane warned that cutting back on defense spending "would be a huge mistake." Instead, Keane argued, the administration would need to sustain its large increases in the defense budget.

He's also had harsh words for Mick Mulvaney, Trump's deficit-minded budget director and acting White House chief of staff.

“I think there’s a fox in the chicken coop, and that fox is the director of the OMB,” Keane said.

In an interview with NPR on Thursday, Keane said he and Mattis were "of one mind in opposing" Trump's Syria decision and added that he didn't want Mattis' job.

"I don't intend to go back into public service," Keane said. "I'm confident the president will be able to find ... a capable person to serve the nation."



Sen. Tom Cotton



Cotton, a member of the Senate Armed Services and Intelligence committees, has developed a reputation as a top defense hawk in just four years in the chamber. A top critic of national security policies in the waning years of the Obama administration, the Arkansas Republican has since positioned himself as one of Trump's top Senate backers.

The 41-year-old former Army officer, who served in Iraq and Afghanistan, has been mentioned as a possible pick for secretary of Defense or CIA director.

But he's also one of the most conservative members of the Senate and has been unafraid to ruffle feathers among his colleagues, so Cotton could have a bumpy confirmation process. It's also unclear if he'd abandon a safe red-state Senate seat for a Cabinet post.



Sen. Lindsey Graham



Perhaps the Senate's most vocal advocate for a muscular military posture and for U.S. intervention overseas, the South Carolina Republican was a protégé of Sen. John McCain (R-Ariz.), the late Senate Armed Services chairman and an outspoken Trump critic.

Graham initially didn't support Trump's bid for the White House, but he has since often aligned himself more closely with president.

Still, a Graham-led Pentagon appears less likely given his and Trump's seemingly divergent views on U.S. military commitments abroad.

The pair traded jabs this week, for example, over Trump's sudden decision to pull U.S. troops out of Syria. After Graham criticized the decision and called on Trump to reconsider, the president hit back, tweeting Thursday that it was "so hard to believe that Lindsey Graham would be against saving soldier lives & billions of $$$."

Graham, a retired Air Force Reserve judge advocate general who was also once floated as a candidate for attorney general, is likely to chair the Senate Judiciary Committee next year in the new Congress. There, he'll shepherd Trump's slate of picks for the federal bench.



Deputy Defense Secretary Patrick Shanahan



A former Boeing executive, Shanahan has been a vocal booster within the Pentagon for Trump’s Space Force. In November, he brushed back an Air Force estimate that standing up the force would cost $13 billion, saying it should cost much less.

He’s a frequent visitor to the White House and, due to his corporate background, would bring a different perspective than a retired general.



Former Sen. Jim Talent



The Missouri Republican was widely mentioned as a possible Defense secretary two years ago before Trump tapped Mattis. He has broad experience with Middle East and Asia issues and served on the U.S.-China Economic and Security Review Commission.

But things have changed since Talent was last in the running. During the 2016 presidential transition, he reportedly enjoyed the support of incoming White House chief of staff Reince Priebus, who has long since departed the White House.



Director of National Intelligence Dan Coats



A former Republican senator from Indiana, Coats has kept a relatively low profile since taking charge of the nation’s intelligence arm. He’s joined other administration officials in taking a hard line on Russia and the extent to which it interfered in the 2016 election.

His stock dropped in July, however, because of how he reacted to learning in front of an audience that Trump had invited Russian President Vladimir Putin to Washington.

“That’s going to be special,” Coats quipped to moderator Andrea Mitchell during an appearance at the Aspen Security Forum.