One of the front-runners to be Democrat Hillary Clinton's running mate is a retired admiral and defense strategist whose last military post was commanding U.S. and NATO forces in Europe.

Retired Adm. James Stavridis is being considered as a pick who would bring the presumptive nominee national security expertise accrued over his 37-year career, The New York Times reported.

Stavridis is the dean of the Fletcher School of Law and Diplomacy at Tufts University in Medford, Massachusetts, and is viewed as a mainstream foreign policy thinker who, like the former secretary of state, advocates for robust American military presence and political engagement with the rest of the world. That's in contrast to Republican nominee Donald Trump, who has called into question long-standing alliances with Japan and NATO, which he once led as Supreme Allied Commander Europe.

Stavridis is an outspoken critic of Russian President Vladimir Putin’s military-led annexation of Crimea from Ukraine and has called for bolstering NATO in response. He criticized Trump Thursday after the Republican nominee appeared to waffle on his commitment to mutual defense of NATO allies if Russia were to attack them, according to a interview with The New York Times.

Trump on NATO: deeply dangerous will dismay our closest Allies but great cheer in Kremlin: I can hear Vladimir Putin chortling from here. — stavridisj (@stavridisj) July 21, 2016

Lawrence Korb, an assistant secretary of defense for the Reagan administration from 1981 to 1985 , said that if Trump had picked outspoken Obama critic retired Army Lt. Gen. Michael Flynn as his nominee, Stavridis would have made a good counterpoint.

"He would certainly bring military experience as well as foreign policy understanding, and those are things she seems to value," said Korb, a retired Navy captain and defense expert with the liberal Center for American Progress think tank.

Experts said picking Stavridis would also head off another traditional Republican attack line, that Democrats are weak on foreign policy. Trump’s campaign has already blasted Clinton’s time at the State Department and the "disastrous Obama/Clinton foreign policy."

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"The Clinton campaign is pretty good at thinking around the corner and in the fall she will probably be attacked as weak on foreign policy," said Dan Palazzolo, a political science professor at the University of Richmond . "One way to stave off on that, is to consider someone who is extensively and unquestionably qualified to speak about the military and alliances."

The recent attacks from Trump on NATO and suggestions that he will rework decades-old agreements with Europe and Asian allies might also work in Stavridis's favor, Palazzolo said.

"It might not be a bad thing to have authoritative knowledge of NATO to answer questions about it during the convention," he said. "If she wants to articulate the pro-NATO alliance position, she has a voice for that."

Clinton is also reportedly considering prominent politicians like Sen. Tim Kaine, of Virginia, and Agriculture Secretary Tom Vilsack, who can boost her appeal in battleground states.

Taking chances

Stavridis has not shied from criticizing the Obama administration’s policy since in the three years since his retirement, including criticizing the military’s drawdown while it’s still at war.

"We have already cut defense … about 30 percent over the last 10 years, and we're still at war," Stavridis said in a 2015 radio interview. "We're actively involved on multiple continents in real combat operations. We should not be drastically reducing our troop levels."

In recent years, Stavridis has emerged as a frequent critic of Putin's aggressive actions that have unsettled eastern Europe. In a 2014 Navy Times interview, he said Putin was playing to a domestic audience but he would ultimately be "a failure."

"What I think you are seeing is a Putin who is tactically very successful: by undertaking an annexation of Crimea; a destabilization of Ukraine," Stavridis said. "[But] Where is he successful? He's successful in Russia. That's the audience for those activities. He is banging the drum of Russian nationalism louder than we've seen it in 50 years.

"Those tactics help him immeasurably at home to maintain control and to feed the fires of Russian nationalism. He's going to be tactically successful in those regards. He's going to be a strategic failure."

Stavridis brings command experience at every level. The surface warfare officer commanded destroyer Barry from 1993 to 1995, led Destroyer Squadron 21 and headed the Enterprise Carrier Strike Group from 2002 to 2004. He would later go on to command U.S. Southern Command, where he developed tactics to disrupt increasingly sophisticated drug trafficking trends like narco-submarines.

In 2009, he became the NATO's Supreme Allied Commander Europe. He penned a memoir about his four-years in that post, "Accidental Admiral."

Stavridis was also considered for other top military posts by the Obama administration, but reportedly dropped out of contention after an inspector general investigation into his travel as NATO commander surfaced. The IG cleared him of any misconduct and he retired in 2013.

Stavridis, a 1976 Naval Academy grad, gained a reputation in the Navy for prolific writing, taking an unusually high profile for a mid-grade officer. He didn't shy away from some controversial topics and said he had gotten pushback from some of his articles.

"So you take chances," he told Navy Times in a 2013 phone interview. "You write. But overall, I think that's an obligation to share your ideas. It's how we move forward with innovation."

Stavridis kept a personal diary from his time commanding the Barry, which later became the basis for his memoir, "Destroyer Captain: Lessons of a First Command." The book offers an unvarnished account of his time in command and on deployment, including his failures and anxieties.

""In the end, command is not about competing with anyone but yourself," he said.

Bryan McGrath, a retired destroyer skipper and influential consultant with The FerryBridge Group, said he would be an excellent vice president. McGrath said he's known Stavridis for over 27 years , calling him a rare breed "who is accomplished and successful and who has not, along the way, created enemies."

But the pick is probably not right from a political standpoint because Clinton's foreign policy and national security bona fides are not in question.

In 2009, he became the NATO's Supreme Allied Commander Europe. He penned a memoir about his four-years in that post, "Accidental Admiral."

Stavridis was also considered for other top military posts by the Obama administration, but reportedly dropped out of contention after official travel discrepancies arose; he was cleared of any misconduct, however, and retired in 2013.

Stavridis, a 1976 Naval Academy grad, gained a reputation in the Navy for prolific writing, taking an unusually high profile for a mid-grade officer. He didn't shy away from some controversial topics and said he had gotten pushback from some of his articles.

"So you take chances," he told Navy Times in a 2013 phone interview. "You write. But overall, I think that's an obligation to share your ideas. It's how we move forward with innovation."

Stavridis kept a personal diary from his time commanding the Barry, which later became the basis for his memoir, "Destroyer Captain: Lessons of a First Command." The book offers an unvarnished account of his time in command and on deployment, including his failures and anxieties.

""In the end, command is not about competing with anyone but yourself," he said.

If chosen, Stavridis would be the first admiral on a major party ticket since retired Vice Adm. James Stockdale ran with indepedent Ross Perot in 1992.