MANCHESTER, N.H — We are finally seeing the incredible shrinking Republican presidential field. Chris Christie's withdrawal is the latest reminder that Donald Trump can routinely get away with what the other candidates cannot.

Consider: Christie clearly hurt Marco Rubio in Saturday night's heated exchange about the Florida senator's readiness to be president. But the New Jersey governor didn't obviously help himself either, and may have suffered some self-inflicted wounds in the process.

It's easy to remember that Christie first rose to conservative stardom because of YouTube videos showing him not taking any guff from Democratic questioners at town halls. Some of Christie's interlocutors had generally been thought of as sympathetic figures: schoolteachers, albeit unionized ones, Hurricane Sandy victims with complaints about how the relief aid was being distributed.

Go online and it's not hard to find videos titled "Chris Christie gets into a shouting match with an idiot" or "Christie tells man to sit down and shut up." Christie "destroys" various questioners, reporters and opponents on YouTube going back to his first term as governor. (The most recent example can be found in the titles of videos describing his exchange with Rubio.)

Yet Christie's bravado and Jersey tough guy routine haven't aged as well as "Sopranos" reruns or 1970s Springsteen albums. His shtick seems to repel as many people, even conservatives, as it attracts. Trump can talk to people the same way, sometimes saying things even Christie wouldn't dare utter, and it's no problem.

After spending a not insignificant chunk of time in Iowa and getting some high-profile local endorsements (not including Gov. Terry Branstad's not-too-thinly veiled enthusiasm for his fellow governor's candidacy), after the Des Moines Register published a listicle outlining "7 reasons Chris Christie is poised for an Iowa bump," he finished tenth in the caucuses.

How bad was this showing? Christie ran behind three candidates who, like him, have already dropped out of the race. He finished ahead of only one other contender, Rick Santourm, who was actively contesting Iowa. He did worse than several candidates who were not.

Christie did a bit better in New Hampshire, but he needed to do a lot better. Despite helping Rubio to a dispiriting fifth place finish, Christie won some 9,000 votes behind the Florida senator and failed to earn any delegates or break 10 percent of the popular vote.

For Christie, New Hampshire was probably a must-win state. He was as far from victory as his beloved Dallas Cowboys with quarterbacks other than Tony Romo under center.

If it weren't for the Bridgegate scandal, Christie likely would have become the Republican donor class' candidate and it's possible Jeb Bush wouldn't have even run. Instead he was part of an ineffectual group of establishment candidates famous mainly for damaging Rubio.

Before Christie lost the establishment, he lost conservatives. While there was much in his New Jersey record for the right to dislike, the main issues were symbolic. He hugged Barack Obama. He fought with congressional Republicans over Sandy spending. Asked to deliver a high-profile speech at the Republican National Convention attacking the president and boosting Mitt Romney, he devoted much of his time to bragging about himself.

Down to the "boy in the bubble" jibe against Rubio, can't imagine Trump doing all these things? In fact, he has done all these things and worse. Christie gets too cozy with Obama when they are collaborating on an issue of legitimate public concern in New Jersey. Trump donates money to Hillary Clinton and leading Democrats, transparently justifies it as rent-seeking and continues to lead most polls of Republican voters, including some who boast of being true conservatives.

Carly Fiorina's exit also reminds us that Trump plays by a different set of rules. Sustained criticism of his business record, though probably not as focused as that which greeted Romney in 2012, has failed to gain traction. People are still applauding at Trump rallies and chuckling at the familiar laugh lines.

Fiorina's once-promising campaign could not survive a few unflattering profiles of her time as Hewlett-Packard CEO and her failure to build upon her initial repertoire of jokes and anti-Hillary zingers.

The surviving not-Trump GOP candidates are hoping one day that Trump falls back down to earth. They thought maybe his high unfavorable ratings at the end of the Iowa phase of the campaign was a sign he was about to do so. After New Hampshire, it looks like they'll have to keep waiting.

One other campaign also seems to be immune from the normal rules. How much longer can Jeb hang on? Bush seemed genuinely pleased with himself Tuesday night in Manchester that he came in fourth. His campaign was dropping hints they'd be satisfied with fifth. In Iowa, they came in sixth.

We're talking about tens of millions of dollars spent in New Hampshire alone by the son and brother of the last two Republican presidents. It's all done little for Bush and has yet to derail the main target of his spending, although some of what the former Florida governor has said will come back to haunt Rubio if he is the nominee.

It's this kind of establishment ineptitude that keeps Trump's routine fresh and his candidacy ahead in the polls.