Ted Cruz sets sights on 'moderate' Marco Rubio

In 2010, Rubio waged a long-shot bid fueled by right-wing groups to defeat GOP establishment favorite Charlie Crist and went on to become one of the mascots of that year's tea party wave. His Senate voting record is anything but moderate, featuring routine opposition to bipartisan deals to avert government shutdowns and debt default, as well as rejecting popular Democratic-led proposals such as raising the federal minimum wage and toughening equal pay for women laws.

As a result, Rubio has scored a rating of 90 percent from Heritage Action, 93 percent from the Club For Growth and 98 percent from the American Conservative Union, three conservative groups that grade Republicans on purity. By contrast, Cruz's ratings are 98 percent, 96 percent and 100 percent—not a huge difference. Both are far above the GOP average and rank among the most ideologically conservative senators.

"If we separate ourselves from the current universe that is the Republican Party, Rubio is at the right end of the spectrum," said Norm Ornstein, a congressional scholar at the American Enterprise Institute.

In 2013, Rubio made a major exception and broke with conservative orthodoxy to work on a comprehensive immigration reform bill, which he later turned against in the face of intense right-wing opposition. That is shaping up to be a sticking point—a pro-Cruz super-PAC recently released a radio ad in Iowa attacking Rubio's "amnesty bill." Cruz's campaign and various super PACs have no shortage of money to go after Rubio, should they want to—they've raised well over $60 million combined this year.

Ornstein said Rubio's turn against the immigration bill forfeits claims he might make to being a moderate problem-solver. "It is only compared to Ben Carson, Ted Cruz, Mike Huckabee, Louie Gohmert or Allen West that you could consider Rubio moderate," he said. "So I guess by the standards of an insurgent outlier party, he is moderate."

Cruz and Rubio also differ on trade—Cruz voted against fast-tracking Obama's Trans-Pacific Partnership trade deal while Rubio voted in favor of it—but neither position is disqualifying on the right.

Stylistic differences

The most important differences between the two men are not on policy, but rather in their respective styles. Rubio typically steers clear of combustible rhetoric and has a good reputation among Republican leaders, elites and donors (such as billionaire Paul Singer). Cruz, on the other hand, often assails his own party's leaders as traitors to the conservative cause when they cut deals with Democrats, which has earned him the admiration of the conservative base and the scorn of GOP colleagues and leaders, including being branded a "jackass" by former House Speaker John Boehner

Rubio rejects the idea that he's an "establishment candidate." If true, he recently told Newsmax, "I'd be raising a lot more money." His campaign declined to comment on Cruz's remarks about him.

Cruz sought Rubio's endorsement while running for the Senate in 2012, according to the New York Times, but won without it. The following fall, after Rubio embraced Cruz's push to force a government shutdown if the Patient Protection and Affordable Care Act (PPACA) wasn't defunded, the Texan heralded the Floridian as "a critical national leader" in a floor speech on September 24, 2013. Cruz said, "I don't know if there is anyone more effective, more articulate, or a more persuasive voice for conservative principles than my friend Marco Rubio."