(CNN)The next possible US secretary of defense went by the military call sign “Chaos.”
Revered by his troops as a “warrior monk” with a knack for hard-edged quips, retired Marine Gen. James Mattis led troops in Afghanistan in 2001, won laurels for leadership in one of the bloodiest battles of the Iraq War and most recently headed US Central Command, perhaps the military’s most complicated and challenging post.
Now, Mattis faces an entirely different kind of fight.
As President-elect Donald Trump prepares to formally nominate the former four-star to head the Pentagon, some Democrats are signaling his confirmation might not be entirely easy. Some observers question whether Mattis’ battlefield experience prepares him for the very different task of running an enormous bureaucracy, while senior lawmakers worry about what the 66-year-old’s nomination means for maintaining civilian control of the military.
Republicans issued glowing testimonials to Mattis and his career. California Rep. Devin Nunes, who heads the House Permanent Select Committee on Intelligence, said he could think of “no better candidate to lead America’s military in our long fight against jihadism and countering other pressing threats.”
Noting that Mattis hasn’t been out of uniform long enough to lead the Pentagon without a congressional waiver, California Democratic Rep. Adam Schiff said that while he “would make an excellent Secretary of Defense, we must also bear in mind the precedent we would be setting and the impact it would have on the principle of civilian leadership of our nation’s military.”
Kirsten Gillibrand, the ranking Democrat on the Senate Armed Services Committee subcommittee on personnel, was more definitive.
“Civilian control of our military is a fundamental principle of American democracy,” Gillibrand said in a statement Thursday, “and I will not vote for an exception to this rule.”
Just one senator can demand that the waiver for Mattis meet a 60-vote threshold, meaning he would need to get the support of all Republicans and eight Democrats to move toward confirmation next year.
If he’s approved, Mattis would be the highest-ranking former officer to serve as defense secretary. The Washington State native and history major led troops through the conflicts in the Persian Gulf, Afghanistan and Iraq. From 2010 to 2013, he led Central Command, which oversees the Middle East and Southeast Asia, until the Obama administration let him go over disagreements on Iran.
The White House was pushing for a nuclear deal with Tehran in 2013, the same year Mattis was telling the Aspen Security Forum that his top concern as Centcom commander was “Iran, Iran, Iran.”
Mattis has since been critical of the deal and of the Obama administration’s refusal to engage more aggressively in the Middle East, saying it has fueled extremism in the region. In 2015, he told a congressional panel that the US needed to come out of its “reactive crouch” in the Middle East and defend its values.
Indeed, Mattis has not been known to mince words. He’s affectionately known as “Mad Dog” by troops who trade his quips like prized baseball cards. On the news of his nomination, many of those sayings instantly became memes on Twitter. Among them: “a good soldier follows orders, but a true warrior wears his enemy’s skin like a poncho,” and “be polite, be professional, but have a plan to kill everybody you meet.”
Human Rights Watch called on Congress to fully examine his views on a number of issues.
“Media accounts suggest that Gen. Mattis doesn’t agree with President-elect Trump’s more outrageous campaign proposals, such as bringing back waterboarding, targeting terrorist suspects’ family members, or tampering with anti-torture laws,” said Washington director Sarah Margon.
She urged that during the confirmation process “senators make sure Mattis unreservedly repudiates these proposals,acknowledges that they are illegal, and confirms that they are not up for future consideration.”
Mattis is one of a slew of generals Trump has been considering for other Cabinet-level jobs, including Gen. David Petraeus for the State Department, Gen. John Kelly to head Homeland Security and Adm. Mike Rogers as the director of national intelligence.
Erin Simpson, a national security consultant and senior editor at WarontheRocks.com, said the incoming administration may be trying to capitalize on public respect for the military by considering so many generals. But “where there are really weak civilian institutions and an inexperienced president, it just doesn’t sit right by me,” said Simpson.
The silver lining, she adds, is that many military and security professionals wary of Trump may be convinced to serve under Mattis.
“It provides some top-cover for other qualified folks to come in who might not have otherwise,” Simpson said. “There are a lot of jobs to fill at the Pentagon, this could bring in some talent and that’s a net gain.”