There are plenty of political punches being thrown around the GOP field these days. Christie knocks Bush. Bush knocks Trump. Trump knocks Cruz ... you get the point.

But this past week, they've homed in on one particular punching bag: Marco Rubio. It's one side effect of his better-than-expected third-place finish in Iowa and subsequent growth spurt in New Hampshire. As NPR's Scott Detrow recently reported, there is Marco-mentum in the Granite State — something a flurry of new polling data support.

The punches are varied — some say the first-term Florida senator is inexperienced. Some say he's inconsistent. And others question how his loss in Iowa is being spun into a quasi-victory.

Even though New Hampshire is a key state for any traditionally moderate candidate, Rubio has arguably become the most popular candidate to criticize.

That's partly because Rubio is trying to portray himself as a candidate for all Republicans — a possible bridge builder who could coalesce Tea Party and traditional establishment support around him. At campaign events, you meet people torn between Rubio and Ted Cruz, but, just as often, you meet people torn between Rubio and John Kasich. So Rubio's rivals (both insiders and outsiders) feel universally threatened by the 44-year-old's potential.

Here's how the fight has played out this week.

ROUND 1: The Governors

Before the results for the Iowa caucuses were even tallied, Rubio's fellow Floridian had already begun launching attacks. Former Florida Gov. Jeb Bush told a crowd Monday evening that Rubio (and Cruz) were "backbenchers" who had "never done anything of consequence" in their lives. He described them as talented speakers, but not leaders.

Then, on Tuesday, New Jersey Gov. Chris Christie joined the chorus.

"We know who the boy in the bubble is up here who never answers your questions, who's constantly scripted and controlled because he can't answer your questions," Christie said. "So when Sen. Rubio gets here, when the boy in the bubble gets here, I hope you ask him some questions."

ROUND 2: The Donald

Donald Trump — who has essentially led every New Hampshire poll for months — seemed less threatened and more perturbed by the newfound Rubio attention when he spoke to thousands at an indoor tennis club Tuesday night.

He described Rubio as a "nice guy" but then questioned the media's narrative out of Iowa.

Trump's main complaint centered on optics; he didn't appreciate being dubbed a "loser," while the candidate who finished behind him (Rubio) was dubbed a "winner."

"The headlines were 'Trump comes in second. He's humiliated.' I come in second, I'm not humiliated," Trump said.

ROUND 3: The Real Iowa Winner

Cruz, the man who actually won the Iowa caucuses, began his post-Iowa tour with nuanced policy-specific attacks. He questioned, for example, Rubio's immigration position.

"Marco made the decision, the conscious deliberate decision to go and stand with Barack Obama, and Chuck Schumer and Harry Reid and to lead the fight for amnesty," Cruz told voters at a small church in New Hampshire Tuesday.

But his tone quickly changed. And the attacks morphed from policy issues to personal issues.

"You know, we've been joking — [that] in the media world that bronze is the new gold," Cruz told Fox's Sean Hannity late Tuesday. "They're going to push the candidates that they want to push, and the Washington cartel has its favorite candidates."

ROUND 4: The Governor Hits Again

By midweek, Christie was ready with more intense insults.

The New Jersey governor suggested Rubio was unfairly benefiting from a media bump in the aftermath of the Iowa caucuses. Here's an excerpt from an interview with The Washington Post:

" 'It's like you're writing Rubio press releases,' he said. 'Seriously. The guy was predicted to come in third, and he came in third. So what was the great shock? I said all along I felt it would be Cruz-Trump-Rubio. It was Cruz-Trump-Rubio. Yawn.'"Christie added: 'All of a sudden, he's now the consensus nominee? Come on. It's silly. ... After 180,000 people in Iowa voted?' "

And in an interview with MSNBC's Morning Joe, Christie's attacks grew more personal.

"The problem is with someone like Marco Rubio, who quite frankly hasn't proven that he can get anything done except to get up in the morning, you know, fix his hair, smile and give the same speech he's given for the last six years," Christie said. "I don't understand how that's a qualification for president of the United States."

New Hampshire is a key state for Christie, who skipped the Iowa caucus celebrations Monday evening in the state. Christie has said he needs to beat both Bush and Kasich to sustain his campaign. And now he sees Rubio potentially peeling away voters crucial to his strategy.

That's why Christie's campaign is going on the offense, ripping into Rubio with such a vengeance. In addition to the jabs above, Christie also mocked a somewhat awkward moment in a Morning Joe interview when former GOP presidential candidate Rick Santorum, who is now endorsing Rubio, struggled to list one concrete accomplishment of Rubio's in the Senate.

Reluctant To Fight Back

As Rubio crisscrossed New Hampshire, holding back-to-back town halls, he seemed reluctant to fight back, although the superPAC supporting his campaign has not shown the same reluctance. Conservative Solutions PAC recently released a negative ad that takes aim at Bush's sputtering campaign.

Rubio, though, is hesitant to engage the critics these days. He is riding high after Iowa. And with a telegenic face, a wide smile and a rags-to-riches immigrant story, Rubio is attracting hundreds of people to town halls across New Hampshire. At two events Thursday, he needed an overflow room for the crowds.

At most of his pit stops, Rubio delivers essentially the same stump speech he has given for months.

He never acknowledges the attacks, let alone his GOP rivals. Instead, he focuses on the Democrats, presenting himself as the party's best choice to beat Hillary Clinton.

"I will unite the conservative movement and the Republican Party," Rubio told a crowd in the traditionally Democratic city of Portsmouth, along the New Hampshire coast. "I will grow the conservative movement and the Republican Party. And, if we do that, we will win. The Democrats do not want to run against me. Consistently, they attack me more than any other candidate in the field because they do not want to run against me."

It's a tactic that allows him to seem above the infighting and focus on a general election strategy, even though he still has an uphill climb to capture the GOP nomination.

When reporters asked Rubio Thursday to respond to his critics, he hedged.

"I think it's silly," Rubio said. "Look, when people are having a tough time in a campaign, especially near the end, you see some desperation set in."

Rubio is trying to stay on message.

"I know this about politics — when everyone's attacking you, you must be doing something right," Rubio told reporters in Manchester.

But whether Rubio can remain aloof and ignore the critics through primary day on Tuesday isn't clear. After all, he will face his rivals eye-to-eye in a debate Saturday. And it's much harder to dodge the blows when everyone will be in the same boxing ring.

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