Russian President Vladimir Putin holds an award during a meeting of Russian Geographical Society in St Petersburg, Russia, Monday, April 27, 2015.

Russian President Vladimir Putin holds an award during a meeting of Russian Geographical Society in St Petersburg, Russia, Monday, April 27, 2015. Kremlin Pool Photo via AP

Putin Bad, GOP Candidates Agree

Less clear is what they’d do, as America's next president, about a more assertive Russia.

He's someone who John McCain says rules "by corruption, repression, and violence." He's someone Joe Biden says has no soul. He's sometimes flamboyantly shirtless. And for Republican presidential candidates, he's someone who can pull the primary field toward a sense of nationalism found in the corners of the Far Right, without the risk of alienating most voters.

Vladimir Putin is not popular in the United States. Last February, during the Winter Olympics, the Russian president and his country saw their highest unfavorable Gallup ratings in 20 years. That was before Moscow took Crimea from Ukraine a month later. This February, another Gallup poll found that Russia replaced North Korea as the country Americans consider to be their greatest enemy. Unlike in 2008, when Mitt Romney said Russia was the nation's No. 1 geopolitical foe and Barack Obama scoffed, Republicans (and Democrats) don't have to work hard to convince voters that their next president needs a plan to handle Russian aggression.

Putin is a question that Republican contenders can count on to get right on the campaign trail. He's an easy talking point whose continued intervention in eastern Ukraine allows candidates to do three of their favorite things: bash President Obama's attempt to "reset" relations with Russia, bash Hillary Clinton's attempt to implement that reset, and bring up Ronald Reagan, the conservative hero who told Mikhail Gorbachev to tear down that wall.

When it comes to Russia, Republicans don't have to distinguish themselves from their challengers. Everyone's winning the Putin primary, as conservative radio talk-show host Hugh Hewitt recently called it. They are ready to stand up to him; the question is how tough they're going to be about it. If Putin is going to act tough, Republican candidates are going to act tough, too—and try to one-up each other in the process.

I've got one rule of thumb—any world leader riding around on a horse without their shirt's got a problem. We can handle that guy.
Sen. Lindsey Graham, R-S.C.

"We're beginning to realize the reset button didn't turn out so hot," Jeb Bush said last week during a visit to Germany, a few days before announcing his candidacy for president. He also called Putin a "bully."

Carly Fiorina agrees. "I have met Vladimir Putin, and I know that his ambition will not be deterred by a gimmicky red reset button," she said in February.

(See also: On National Security Cred Tour, Jeb Shakes Fist at Putin)

"If I were ever elected, there's a lot of things people might say about [my] bluntness, directness, and straightforwardness, but I will tell you this: Vladimir Putin would never have to wonder what I thought was acceptable and what was unacceptable," Chris Christie, who is expected to decide on a 2016 run this month, said last week, using a go-to Republican dig against Obama's inability to "stand up to Putin" that drips with machismo.

Ted Cruz used it last summer, when he invoked Reagan: "'Mr. Putin, give back Crimea.' Why is it so unimaginable for President Obama to utter those words?" In the Ukraine crisis, Cruz said, "the Russian bear is encountering the Obama kitty cat." After Crimea's annexation, Marco Rubio wrote an op-ed in The Washington Post titled "Making Putin pay."

Lindsey Graham once said: "I've got one rule of thumb—any world leader riding around on a horse without their shirt's got a problem. We can handle that guy."

Rand Paul learned early to err on the side of toughness. Last February, Paul said the United States shouldn't antagonize Putin over the brewing Ukraine conflict, distancing himself from the prevailing party sentiment at the time, and then backtracked a few days later with decidedly more aggressive words in an op-ed in Time. "If I were president," he wrote, "I wouldn't let Vladimir Putin get away with it."

Presidential elections rarely hinge on foreign policy, but candidates haven't seized on the threat of Russia—and on the electorate's distrust of it—this much since perhaps the 1984 race. Recall this eerie ad from Reagan's reelection campaign warning Americans that "some say the bear is tame; others say it's vicious and dangerous."

Campaigning on Putin—the "ruthless pragmatist," the unsmiling face of "the Russian bear"—allows Republican candidates (and Democratic ones) to slide on offering prescriptions for how to actually deal with his government. Most Republicans agree that the United States should impose more economic sanctions, establish an American military presence inside the borders of Russia's neighbors, and give Ukraine weapons to fight pro-Russia separatists—all options the Obama administration is considering. But they don't have to lay out the specifics of their own Russia policies. Few are there to tell them what's wrong or right, including the White House, which hasn't yet figured it out, either.

(Read more: The Russian Weapon That Could Tip The Balance in the Middle East)

In an interesting twist, the candidate who has gone toughest on Putin, the real winner of the Republicans' Putin primary, isn't even in it. At a private fundraiser in March 2014, Clinton compared the Russian government to Nazi Germany, saying that Putin's justification for entering Crimea—to protect ethnic Russians there from Ukraine—was similar to "what Hitler did back in the 1930s."