New Jersey Gov. Chris Christie (R) slaps down Sen. Marco Rubio (R-Fla.) for trying to “slime” his way into office and says he “ran away” from immigration reform. Rubio’s super PAC calls Christie a clone of President Obama. Both attack Sen. Ted Cruz (R-Tex.) over the National Security Agency. It must be less than four weeks before the Iowa caucuses and five weeks before New Hampshire.

Is it horrible, I mean, these Republicans attacking one another? Of course not. It’s an election and it is perfectly legitimate to debate Rubio’s experience and toughness, Christie’s record and ideology. None of this is out of bounds. It does, however, tell us a lot about the race.

To begin with, neither is bothering to attack Jeb Bush. Rightly or not, his opponents do not see him as a threat. They both believe that after New Hampshire Bush will be hard-pressed to continue on, especially if he finishes behind both of them.

Neither is bothering to attack Donald Trump. It’s not in their interest at this point to weaken Trump, which would only boost Cruz’s prospects. Moreover, neither is vying for the Trump segment of the electorate; they are running right now to be the guy who unifies everyone else in the party against Trump or Cruz.

Neither is bothering to attack Ohio Gov. John Kasich. The Post reports that “when asked about Kasich, Christie deadpanned: ‘Kasich. John Kasich? He’s attacking me from the right? Okay. From the right? I mean, come on. Please.'” Ouch.

Christie and Rubio know the number of competitors in their “lane” of the primary (candidates seeking support from moderate and somewhat conservative Republicans) has to narrow in order to swamp Trump and/or Cruz.  The Christie-Rubio dynamic is arguably the most interesting face-off right now because both candidates are skilled and have a real shot at securing the top spot in the not-Trump-or-Cruz contest.

Ideologically there really is not all that much difference on policy between Rubio and Christie. Both are tough hawks. Both have tax-cutting plans. Both favor repealing Obamacare. Both are pro-life. But there are some points of disagreement between the two. Rubio is sticking to his path-to-citizenship position on immigration; Christie has been less clear about the ultimate resolution for the 12 million here illegally, but now calls the Gang of Eight “amnesty.”

The starkest differences, however, are in personality and biography. It’s the savvy executive against the adroit legislator. Christie is the more intuitive, spontaneous pol; Rubio is the more refined and eloquent. Christie has the crisis-management chops and loves to put down senators as people who don’t actually do much of anything. Rubio touts his foreign policy sophistication and can portray himself as an easier sell with the right wing in his party. Christie would unload on Hillary Clinton in a debate; Rubio would dissect her failures. Rubio wants to be liked; Christie wants to be respected, if not feared.

They’ve also had different approaches to the race. The risk for Rubio is that he does not win a state early on. The risk for Christie is that he doesn’t beat Rubio, Bush and Kasich in New Hampshire. Rubio has planned for the long haul. Christie will rely on post-New Hampshire momentum.

Gravitas or charm? The blue-collar guy or the policy maven? That’s the choice facing GOP voters looking for a hawkish conservative with concrete reform plans, someone who can carve up Clinton and win over swing voters. Christie may be the pugnacious, thinking-man’s Trump. Rubio shouldn’t be annoyed to be called the GOP’s Barack Obama (i.e. an inspirational speaker who can soften the hard edges in pitching to voters who don’t naturally support his party). It should be a fascinating contest.