Why Cruz's rivals can't make much headway by attacking him on issues

Marco Rubio is trying to turn Ted Cruz into Rand Paul. So far this effort is failing.

Sen. Paul, R-Kentucky, has been portrayed as an isolationist. He says he is actually a realist who merely wants to limit our foreign interventions to those serving the national interest. But the description of him as out of step with most Republicans on foreign policy has stuck.

In a speech in New Hampshire, Texas Sen. Rubio, R, decried "isolationist candidates more passionate about weakening our intelligence capabilities than about destroying our enemies." Candidates, plural: Cruz is lumped together with Paul. It is true that Cruz, like Paul, argues for placing more emphasis on protecting American security and less on promoting democracy abroad. Also like Paul, he says he wants anti- terrorist investigations to respect Americans' privacy rights.

But I don't think Cruz will be pushed to the margins of the party the way Paul has been. While my friendship with Cruz may cloud my judgment, I can see five reasons for doubting that Republican primary voters will conclude he is weak on national security.

First: Most Republican voters themselves oppose overseas intervention when they do not think it would advance an important national interest. In 2013, when President Barack Obama called for airstrikes against Syria, some GOP leaders supported him -- but most Republican voters disagreed. In a 2012 survey, while 76 percent of Republicans listed stopping the spread of nuclear weapons and 73 percent listed fighting terrorism as "very important" foreign-policy goals, only 11 percent listed promoting democracy. So when Cruz expresses skepticism about that idea, Republican voters don't recoil in shock -- especially since Cruz also sounds just as gung-ho as Rubio about "destroying our enemies." Similarly, most Republicans share Cruz's concern about mass surveillance.

Second: Cruz isn't asking primary voters to make a break from their long-held views on these issues. It's true that George W. Bush generally enjoyed strong support from Republican voters and often spoke of an active foreign policy oriented toward expanding freedom. But that rhetoric wasn't why Republican voters supported him. They favored the Iraq war in 2003 for the same reason the public at large did: They thought Saddam Hussein's regime posed a threat to U.S. interests because they believed it was trying to acquire nuclear weapons. Only after that belief was disproved did the promotion of freedom become the central rationale for Bush's foreign policy.

Third: Most primary voters don't have detailed views on the specific disputes at issue. Rubio says that overthrowing the Bashar al-Assad regime has to be central to U.S. Syrian strategy, while Cruz says that path risks empowering the Islamic State. Rubio thinks the National Security Agency is now too hamstrung to do effective surveillance, while Cruz says recent changes have improved its ability to do its job. Most people don't know what to think about these issues (in contrast to, say, the matter of granting legal status to illegal immigrants, where voters' views are much clearer). So as long as Cruz and Rubio both seem reasonable and serious on foreign policy and pass various easily understood litmus tests -- they're for Israel, and against cutting the defense budget -- they will both seem like commander-in-chief material to Republican voters.

Fourth: The foreign-policy and security issues are tricky for Rubio, too. It's not that Cruz's attacks on him will move voters, either: Again, I think the arguments get too in-the- weeds to do that. Rather, it's that Rubio can't take a clean shot at Cruz. Rubio's latest claim is that the terrorists, if they could, would have lobbied for the new law that Cruz backed regulating NSA surveillance. But that law passed with strong bipartisan support. And it passed with the support of prominent Rubio backers. Right after Christmas, Rubio's campaign touted a statement from Republican Representative Trey Gowdy that endorsed Rubio on national-security grounds. But Gowdy was a co- sponsor of the law that Rubio wants voters to consider pro- terrorist.

Fifth: Cruz isn't Rand Paul. The Kentucky senator had a record that made it harder for him to shake the isolationist label. Paul has claimed that Dick Cheney pushed for the Iraq war to help Halliburton's business interests. Paul tried to cut aid to Israel. He said Americans were too critical of Vladimir Putin. Referring to Pearl Harbor, he has said U.S. trade sanctions "probably caused Japan to react angrily." And, of course, he backed the presidential campaigns of his father, former Rep. Ron Paul, who is fairly rigidly against foreign intervention. All of this made Paul's claims to be a realist seem like cover for an isolationism he wanted to keep under wraps. Cruz does not come with any of this baggage.

The Texas senator has not allowed any daylight to come between him and conservative Republican primary voters. That's why his rivals can't make much headway by attacking him on issues. That's true of foreign policy as well, as Rubio is probably discovering.

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Ramesh Ponnuru has covered national politics and public policy for 18 years. He is an author and Bloomberg View columnist.