Chris Christie must really hate Marco Rubio.
The New Jersey governor has now twice undermined the Florida senator he affectionately calls "the boy in the bubble" at key points in the Republican presidential race.
The first was when Rubio entered New Hampshire with considerable momentum from a stronger-than-expected finish in Iowa (accompanied by just-as-expected hype from his many admirers on social media). Christie then helped Rubio have his worst moment on the GOP debate stage, sinking the Floridian to fifth place in the primary.
Hours after Rubio had some of his best moments on the Republican debate stage, Christie came out and endorsed Donald Trump. The highlights of Rubio's performance had all come at Trump's expense.
There is probably more to Christie's Trump endorsement than simple anti-Rubio animus, of course. Both Trump and Christie are loud, brash Northeasterners. Both are more authoritarian than libertarian. Both have been accused of using their power and influence to punish perceived slights. Both can be pragmatic and ideologically flexible.
In some cases, Trump took Christie's initial appeal — the tough-talking, New York/Jersey executive who isn't afraid to make a decision or punch a hippie — and amplified it by several notches. In addition to the growing conservative perception that Christie was too moderate, this might have sapped interest in the governor's presidential campaign.
There are also practical considerations if Christie wants a senior position in the next Republican administration (Bridgegate and his 2016 run may have irreparably damaged his political fortunes in New Jersey). If Rubio, Ted Cruz, or even John Kasich wins the Republican nomination, there will be a long list of people with government and political experience lining up for work.
By becoming one of the first few significant Republican elected officials to endorse Trump, and so far the only former candidate for the nomination to do so, Christie is now on the short list for any job he wants if Trump wins. This includes attorney general or even vice president.
Trump-Christie might not wear well nationally. That's a lot of bravado for one ticket. And Trump winning the presidency is still a big if, though it would no longer be a major shock if he secured the nomination.
But it might be better than swallowing your pride and endorsing the boy in the bubble.
Christie's endorsement has angered many of his fellow establishment Republicans, including a former Jeb Bush aide who compared Christie to a fat kid who gives his lunch money to the bully.
Like Rubio, Christie has frequently mocked Trump's loose grasp on policy details. He has also been one of the field's most persistent hawks, blasting the party's war-weary voices for forgetting the lessons of 9/11. Trump, by contrast, has called the Iraq war a "big, fat mistake" and said 9/11 was proof George W. Bush failed to keep the country safe.
Yet Rudy Giuliani, who shares Christie's hawkish views and lashed out at Ron Paul for making comments about Iraq and 9/11 that were restrained by comparison, is a Trump fan too. The three men have similar styles. The two politicians have surely interacted with Trump as a donor to political causes, while Rubio and Cruz have mostly been sources of irritation.
The genuinely important issues that led to Giuliani's election as mayor of New York City in 1993 — crime, corruption, one-party misrule, the sense that New York had become an ungovernable city — had racial undertones like many of the controversies associated with Trump.
Christie has mostly picked fights with government workers and their unions, occasionally rebuking conservatives he thought were engaging in anti-Muslim bias. But he's no stranger to the controversies of the 1990s and likely senses we are in a similar political climate right now.
So it makes a certain amount of sense that Christie is standing with Trump rather than Rubio. And it is no coincidence he made his allegiance known at a time when it was most likely to step on the positive headlines Rubio had generated.
You might say Christie wants to burst Rubio's bubble.