Chris Christie, who ran for president on the sober promise to "tell it like it is" and whose campaign was built around the urgency of entitlement reform and restoring U.S. national security, on Friday endorsed Donald Trump, a national security ignoramus who is running for president adamantly opposed to any serious entitlement reform and whose campaign is built around outrage and egesta.

It's a development that is important, stunning and unsurprising.

Important: The timing of Christie's endorsement was perfect for Trump. The candidate running on strength had been thoroughly emasculated by Marco Rubio and Ted Cruz at the debate in Houston on Thursday. Rubio highlighted his hypocrisy on hiring non-American workers, an attack that left Trump nonplussed during the debate and spinning hard afterwards. Trump defended himself by arguing, a) that he couldn't possibly have known what the Trump bureaucracy had done in its hiring practices, and, b) he had to hire non-Americans because he couldn't find Americans who would do those jobs.

When Cruz pushed Trump on his announced neutrality in the Israel-Palestinian conflict and asked what Trump had done for Israel, Trump noted that he'd marched in pro-Israel parades and received awards from Jewish groups. If Trump were not beyond embarrassment, it would have been a thoroughly humiliating performance. The ridiculing of Trump continued into Friday, with Rubio reading Trump's juvenile tweets during a speech.

Enter Christie. Just as the post-debate narrative focused on Trump in a way that undermined his core attribute – strength – Christie's endorsement not only changed the subject but was itself a sign of Trump's strength.

Most significantly, Christie's endorsement gives Trump legitimacy that he'd previously lacked – and again, the timing was important. The objective of the Rubio attacks, in particular, was to undermine Trump's strength and portray him as an illegitimate, phony leader. Translated: Trump might appear to you as a strong man and a potential leader but he is neither.

In exit polls, Trump has done well with voters who have decided whom to support more than a month out – often winning more of half of those voters -- and he has dominated among voters whose top candidate quality is "telling it like it is." But with the exception of New Hampshire and the aftermath of Rubio's debate, he has lost badly among late-deciders. The endorsement by Christie, whose campaign slogan was "telling it like it is," could win him second-looks from voters who had previously been inclined to dismiss him as unserious.

Stunning: Christie's endorsement of Trump certainly shocked the political world on Friday both because it hadn't leaked in advance and because it so directly contradicted the main themes of Christie's campaign. Christie's case to voters was a simple one: We are in perilous times, facing crises that demand responses from serious leaders who will speak about our challenges with urgency and candor. His campaign focused on national security and the entitlements that are driving the country further and further into debt.

Christie has spent years blasting politicians – Republicans and Democrats – for ignoring the entitlement crisis, accusing them of lacking the will to tackle hard problems. In a speech on entitlement reform last April, Christie said the Obama administration "has put us on a perilous course for both our short-terms and long-term futures" because of its "unwillingness to address our biggest challenges in an honest way" and its refusal to "tell the truth about what we need to do in order to solve our problems." Trump's approach to entitlements is indistinguishable from Obama's.

Christie strongly defended George W. Bush and the policies that kept America "safe for those seven years." His campaign promised to restore most of them. Writing in Slate in December, Jim Newell wrote under the headline, "The Dream of the George W. Bush Presidency is Alive in Chris Christie." He wrote: "There is a fourth Bush running for president now, and his name is Chris Christie… Christie sounds more like a George W. Bush–era Republican than even Jeb Bush, and Jeb Bush sounds exactly like a George W. Bush–era Republican."

With his endorsement of Trump, Christie has chosen to support a man who: a) believes that George W. Bush should have been impeached, b) believes that Bush and his colleagues deliberately lied to take the country into an illegitimate war, c) has propagated unfounded conspiracy theories about 9/11 and its aftermath. (Given Trump's false claims that "thousands" of New Jersey residents celebrated those attacks in the streets, Christie is embracing a man who has slandered the residents of his own state, a particularly disgraceful reality).

Christie further argued one of the top priorities of any new administration would be restoring a proper understanding of allies and enemies – and treating them accordingly. "Our willingness to stand with those who share our values and interests," Christie says, "defines us as a country." He adds: "We need to make it clear to our friends and allies that we stand with them in the cause of freedom, and against all the gathering threats."

The same man who said these things endorsed Trump just days after Trump literally announced that he would not stand with Israel in the cause of freedom and against the gathering threats. Trump said he would remain "neutral" between Israel, one of America's closest allies, and the Palestinians who have embraced terror as a legitimate tool against this ally.

Trump, of course, has aligned himself with Bashar Assad and praised Saddam Hussein as someone who liked to kill terrorists. Trump has also openly defended and praised Vladimir Putin, whom General Joseph Dunford, chairman of the Joint Chiefs of Staff, has said presents the greatest threat to the United States, its interests, and allies. Trump's resolve on even the least controversial aspects of the war against jihadists -- not how to fight ISIS but whether to do so -- has corresponded with the prevailing sentiments of the day. In a September debate, he said we shouldn't be fighting ISIS. He later said we should "bomb the shit out of them."

Christie ran as the candidate who would finally bring a level of seriousness and urgency to national security and entitlements, what he described as our most pressing national problems. With his endorsement of Trump, Christie has embraced a candidate who knows very little about these issues and whose public pronouncements on them contradict virtually everything Christie emphasized during his unsuccessful presidential run.

Unsurprising: In retrospect, Chris Christie's endorsement of Trump should have been obvious. Christie had made clear over his long career that his long career was never so much about issues and policies as it was about Chris Christie. He would "tell it like it is" only insofar as doing so advanced Chris Christie.

This is the guy who came to Washington, D.C., in February 2011, to thunder about the timidity and weakness of Republicans who refused to reform entitlements, and then chose to grow entitlements as governor of New Jersey. He's the guy who declared in that speech that failing to reform Medicaid would lead to the "ruin" of the country and later chose to expand the program as he sought reelection. He called this Medicaid expansion under Obamacare "extortion" by the federal government and then eagerly agreed to be extorted.

This is the guy who endorsed Mitt Romney for president in the fall of 2011, shortly after announcing he wouldn't be running himself, and then demanded that the Romney campaign treat him like he was the candidate himself. When Romney offered Christie the most-desired speaking slot at the 2012 Republican National Convention, Christie used it to talk extensively about himself (more than three dozen uses of "I") and to tout the GOP nominee almost in passing (seven mentions).

This is the guy who urged the Senate to confirm Sonia Sotomayor as a Supreme Court Justice when he was running as a moderate for governor of New Jersey in 2009 but pretended he didn't when he was running as a conservative for president in 2016. When asked about his previous support, Christie offered a categorical denial: "I didn't voice support for Sonia Sotomayor." But a statement from his office at the time was unambiguous. "I support her appointment to the Supreme Court and urge the Senate to keep politics out of the process and confirm her nomination. Qualified appointees should be confirmed and deserve bi-partisan support. Chief Justice Roberts and Justice Alito deserved that support based on their work as Circuit Court Judges. So does Judge Sotomayor. As a result, I support her confirmation."

When I asked him about this last month, Christie first claimed that the two claims didn't contradict one another. Then, when I read his words back to him, he pretended that he'd just meant she deserved an up-or-down vote. When I read them to him yet again, he pointed to two different statements that had been released in his name. And then, when I read them to him a fourth time, he said: " I don't know where that statement comes from."

So, it shouldn't have been surprising that this man who claimed to "tell it like it is" was, like so many other politicians, full of it.

Throughout the course of his campaign, Christie often lamented the lack of seriousness and judgment that Trump had brought to the Republican competition.

At a town hall last summer, Christie said Trump's business skills were not "transferable" to politics and worried that Trump's authoritarian impulses would keep him from accomplishing anything if he were to win. Trump lacks the ability to deal with people who disagree with him, Christie argued. "You have to have some experience in knowing how to deal with people in that way. And he has not shown that over the course of his career," Christie added. Christie made clear that this wasn't an accidental claim or a throwaway campaign line. When his questioner challenged Christie's claim about Trump, Christie gave up trying to persuade her otherwise, saying theirs was a " fundamental disagreement" and that she was welcome to vote for Trump.

Just a couple weeks ago, after he'd withdrawn from the race, Christie told a newspaper that he would never support Donald Trump. The businessman was simply not serious enough to merit his backing.

"Show time is over," Christie had said in December. "We're not casting a TV show. This is real."

The show goes on. And like so many things that have passed the lips of Chris Christie over the years, he didn't mean what he said. So file those words alongside his arguments about the urgency of entitlement reform and his condemnation of Medicaid expansion as extortion. Or place those words between the ones he spoke about standing-by-allies and George W. Bush keeping the country safe.

Christie once lamented that Trump's election would " hurt the credibility of the presidency." He was right. And his willingness to endorse Trump anyway shreds the credibility of Chris Christie.

Maybe, if voters think about these things, Christie's endorsement of Trump won't end up being terribly important. It's little more than a politician with a long history of phony candor offering his support to pseudo outsider who long ago mastered the politician's art of rhetorical feculence.