RUTHFULLY YOURS

The pair of freshmen senators went toe-to-toe several times, most notably on the issues of the National Security Agency’s data collection and immigration, participating in lengthy back-and-forth exchanges that left the other candidates sidelined while CNN featured the budding rivals in a split-screen presentation.

Tuesday may have foreshadowed a Rubio-Cruz battle for the nomination that more and more Republicans are now predicting, as Cruz continues to consolidate the support of conservative voters and Rubio emerges as the favorite of center-right, establishment-oriented voters. The headlines coming out of the Nevada debate could further cement the narrative of a collision course for the two senators, who presently occupy very different places in the Republican field. Rubio, despite strong debate performances, remains stuck in the mid-teens in early-state polling; Cruz this week surged to the top of several Iowa surveys and is gaining momentum nationally.

The looming threat to such a binary battle continues to be Donald Trump, who continues to place at or near the top of virtually every poll in the early nominating states. But the bombastic real-estate mogul was largely absent from the defining moments of Tuesday night’s debate inside the towering Venetian hotel and casino here on the famed Las Vegas strip.

The first direct conflict in the suddenly fierce rivalry between Senate colleagues, heretofore conducted via dueling press releases, came when co-moderator Dana Bash asked Rubio about Cruz’s support for a bill that limited the NSA’s ability to collect metadata from US citizens.

“Is Senator Cruz wrong?” Bash asked Rubio, who voted against the bill. “He is,” replied Rubio. “And so are those who voted for it.” His campaign fleshed out the jab hidden in those words with a press release showing Cruz surrounded by other senators who voted for the bill: Democrats Harry Reid, Chuck Schumer, Al Franken, and Barbara Boxer.

Cruz’s vote, Rubio said, made the country less safe, as Americans are increasingly concerned about national security in the wake of the terrorist attack in San Bernardino, Calif.

“This is not just the most capable, it is the most sophisticated terror threat we have ever faced. We are now at a time when we need more tools, not less tools,” Rubio said. “And that tool we lost, the metadata program, was a valuable tool that we no longer have at our disposal.”

Cruz shot back that Rubio was being dishonest, and then questioned his conservative bona fides.

“Well, you know, I would note that Marco knows what he’s saying isn’t true,” Cruz said. “You know, Mark Levin wrote a column last week that says that the attack ads his Super PAC is running that are saying the same thing, that they are knowingly false and they are, in fact, Alinsky-like attacks like Barack Obama.”

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A short time later they tangled again, albeit in less direct fashion, over questions of military strategy to defeat the Islamic State. Cruz prescribed “using overwhelming air power to utterly and completely destroy ISIS,” referencing the success American troops had when they “carpet bombed” Iraqi forces in the Gulf War. But that conflict was waged against a conventional fighting force, and foreign-policy experts have flatly rejected the idea that ISIS can be defeated with air power alone — a point Rubio made when asked about Cruz’s proposal.

“They cannot just be defeated through air strikes. Air strikes are a key component of defeating them, but they must be defeated on the ground by a ground force,” Rubio said, noting that such a force “must be primarily made up of Sunni Arabs” but would also include U.S. special operators.

But the night’s biggest fireworks, and perhaps their fiercest back-and-forth to date, came when Bash raised the issue of immigration and the senators’ respective roles in the 2013 congressional fight over the “Gang of Eight” bill. It began when Rubio was asked whether he still supports a key component of that bill — a path to citizenship for those who entered the U.S. illegally. Rubio, after detailing the preconditions necessary, reiterated that he does indeed support it.

Turning to Cruz, Bash asked about Rubio’s assertions that the two senators have essentially the same views on immigration. Cruz smirked and let out a soft laugh.

“Well, he has attempted to muddy the waters, but I think anyone that watched the battle we had — there was a time for choosing, as Reagan put it, where there was a battle over amnesty,” Cruz said. “And some chose, like Senator Rubio, to stand with Barack Obama and Chuck Schumer and support a massive amnesty plan. Others chose to stand with Jeff Sessions and Steve King and the American people and secure the border.”

RELATED: GOP Debate: Trump Is Unscathed

But Rubio turned the tables on Cruz, accusing him of supporting massive increases in legal immigration and promoting a path to legalization for illegal immigrants. When Cruz objected, Rubio dared Bash to ask the Texas senator whether he would “rule out” offering legal status to any of the illegal immigrants living in the U.S.

“I have never supported” Cruz began — but Rubio cut him off: “Would you rule it out?”

In a carefully-worded response that could come back to haunt him, Cruz replied: “I have never supported legalization, and I do not intend to support legalization.”

Cruz’s team was giddy in the post-debate spin room, rejoicing that Rubio had finally been pinned down and forced to admit his support for what Cruz has derided as “amnesty.”

“He didn’t deny it; it was very clear that that was his position,” Rick Tyler, Cruz’s national spokesman, said. “And I’m just surprised — shocked actually — that it took five debates for him to be questioned about that decision. It was remarkable.”

Asked about a press release sent by Rubio’s campaign identifying the specific times Cruz has advocated legalization, Tyler replied: “None of them are true. He has never supported a path to legal status.” Cruz’s authorship of an amendment to the Gang of Eight bill offering legal status but not citizenship, Tyler argued, was a “poison pill” meant to derail the legislation.

Rubio’s team, meanwhile, pounced on Cruz saying he doesn’t “intend” to support legalization. Rubio communications director Alex Conant said Cruz “clearly left the door open to returning to his previous position which was to give legal status to illegals that are here,” and summarized their exchange thusly: “I don’t think anybody watching TV tonight didn’t know what Marco Rubio’s position on immigration was. A lot of them still don’t know what Ted Cruz’s position on immigration is because it’s so muddled and uncertain.”

The made-for-TV clashes between the two young senators, both considered once-in-a-generation political talents, blocked out much of the activity elsewhere on stage.

Jeb Bush took on the role of giant slayer, casting Trump as an unserious candidate who is ill-prepared to run the country. Trump flashed his only agitation of the evening when Bush made those remarks, sneering at one point about a recent national poll: “I’m at 42 [percent], you’re at 3 [percent].”

But Bush held his own in the face of Trump’s scoffs and sarcasm, decrying Trump’s proposal to ban Muslims from entering the country and getting in several effective digs without being drawn into a war of one-liners with the GOP front-runner.

“Donald, you’re not going to be able to insult your way to the presidency,” Bush quipped at one point, earning a booming ovation from the audience.

With Bush seizing the role of the adult in the room, other candidates were left gasping for oxygen. John Kasich tried several times to interrupt, but rather than landing a blow, wound up on tangents about Ohio’s economy. Chris Christie offered several well-worn answers that occasionally did not seem tailored to the subject matter being discussed. Carly Fiorina, too, struggled to get in on the conversation. At one point, Bash shut her down when Fiorina attempted to interrupt one of the compelling exchanges between Cruz and Rubio.

Their face off was a boon for another candidate: Rand Paul, who easily jumped into the discussions of the topics on which he has made his name, like metadata collection, nation building, and regime change. Paul had the advantage of a friendly crowd — Paul and his father have a loyal following in libertarian-leaning Nevada — and the senator’s every statement was met with cheers from a small but vocal group of supporters inside the theater.

Trump, a constant thorn in Republican establishment’s side, may have assuaged the concerns of some present when he unexpectedly announced — after pledging earlier this year to run only as a Republican, and then recently threatening to renege — that he will not pursue an independent White House bid.

The one highly-anticipated confrontation that never materialized: Cruz versus Trump. The candidates had until last week refrained from attacking one another, until a New York Times recording surfaced of Cruz questioning Trump’s judgment at a private fundraiser, prompting Trump to say of Cruz on Fox News Sunday, “I don’t think he’s qualified to be president.”

But Trump backed off that assertion Tuesday night, and Cruz yet again sidestepped questions about why he won’t say about Trump publicly what he has said privately. Apparently satisfied, Trump slapped his friend on the back several times and declared with a smile that Cruz is, indeed, qualified.

— Tim Alberta is chief political correspondent for National Review. Alexis Levinson is senior political reporter for National Review.