I was just sitting here contemplating what to write about today when some breaking news made the decision for me: Chris Christie has just ended his presidential campaign. This is going to shake things up in the Republican field, obviously, but will it shake things up enough to make any sort of difference? That remains to be seen.

We won't have to wait very long for the other major candidates' reactions, since Nikki Haley and Ron DeSantis are scheduled to hold their first one-on-one debate tonight on CNN, while Donald Trump will be holding a town hall over on Fox. Undoubtedly all three will be asked at some point to react to the breaking news, so we'll see if Nikki Haley (in particular) can contain her glee.

Christie falling on his sword is entirely in keeping with the rest of his campaign, as he's always said he was running to do his best to deny Donald Trump the nomination. However, Christie always polled terribly in contrast to the rest of the field, especially on the question of likeability. He was the most disliked candidate in the field, according to many polls -- the GOP electorate put him lower than Mike Pence and Vivek Ramaswamy. So Christie never really had any viable shot at winning the nomination. He was running solely to be a spoiler, if he could.

Chris Christie was one of the few Republicans running who still had a firm grasp on reality. This included being able to tell that the 2024 GOP primary race was setting up to be largely a repeat of the 2016 nomination race, except on steroids. Trump would get the most votes, while the rest of the field (the anti-Trump vote) is so splintered that no single candidate could ever build the strength to truly challenge Trump's dominance. In 2016 the field didn't coalesce down to a single challenger until far too late in the contest for it to have any effect on the outcome. This time around, the field has narrowed considerably even before the first votes are cast, so the real question is: will it do any good this time?

The answer to that question might depend on when one of the other main not-Trump candidates decides to call it a day -- a withdrawal from the race that won't be as cut-and-dried as Christie's exit. But I'm getting ahead of myself. First, let's examine how Christie's exit could shift the dynamics of the race in the early-voting states.

Nationally, Christie's polling is pretty low and always has been. Currently, Christie's polling average puts him in fifth place, behind Trump, Haley, DeSantis, and Ramaswamy. His numbers hover in the range of 3-to-4 percent. This has held steady throughout the entire race -- Christie never had either a bump or a dive in the polls. So on a national scale, his exit won't mean all that much.

Christie leaving won't make much of a difference in the Iowa numbers, either. The Iowa caucuses will be held next Monday, and Christie would barely have been a factor even if he had stayed in the race. His polling in Iowa matches his national polling -- between 3 and 4 percent, on average. But while the amount of Christie voters now free to chose someone else may be small, it could also prove to be decisive in one way. Currently, Trump is dominating the Iowa polling and everyone expects him to win next week. His polling average is 35 points above his nearest two challengers, who are neck-and-neck. But that's precisely where Christie's exit could make a big psychological difference.

Nikki Haley and Ron DeSantis have both campaigned heavily in Iowa. Christie completely ignored the state -- he knew he wasn't a good fit for rural evangelical voters, and his campaign funds weren't unlimited, so he concentrated on New Hampshire almost exclusively. Which has led to Haley and DeSantis both currently having just over 16 percent support in the state, to Christie's three or four points.

This is where we get into the game of "Where will they go?" Where will Christie supporters land, now that he's out? The conventional way to answer that is to assume that most of them will go to Haley. If you placed all the candidates on a scale of "how Trumpy they are," the scale would begin with Trump (being the ultimate in Trumpiness), with Vivek Ramaswamy only a hair away in Trumpiness from him. Chris Christie would be at the other end of that scale, with Asa Hutchinson very close to him. These are the only two candidates who ever directly stood up to Trump, said clearly that he wasn't fit to be president, and didn't spend their entire campaign trying to woo Trump's voters by heaping praise on him.

Between these two extremes would fall all the other candidates who ran. Since the ones who have dropped out don't matter at this point, this has now been narrowed down to Haley and DeSantis. And DeSantis is a lot closer to the Trump end of the Trumpiness scale than Haley. While both of these candidates have been seriously reluctant to criticize Trump in any meaningful way, DeSantis built his whole campaign around the concept of "a competent Trump," or maybe "Trump, but without all the dysfunction."

Haley wouldn't exactly be on the Christie end of that scale, but she'd be a lot further away from Trump than DeSantis. She's tried to run her campaign somewhere right in the middle of that scale, in fact. She can be feisty and fight hard during a debate, but she is also grounded in a lot more reality than DeSantis or Ramaswamy. She has been very careful to criticize only individual Trump policies, or Trump agenda items that didn't exactly work out as intended, and has shied away from directly criticizing Trump himself. She has a way of very passively speaking about Trump, as if he were beset by elemental Furies beyond even his control. Her stock, go-to line is: "Chaos follows Trump wherever he goes." Note that construction: it's not Trump's fault -- it is merely the demigods at work, trying to rip him down. She dodged in her recent promise to pardon Trump as well (avoiding the question of whether she thinks he is actually guilty of any crimes or not), by echoing Gerald Ford: "What's in the best interest of the country is not to have an 80-year-old man sitting in jail that continues to divide our country. What's in the best interest of our country would be to pardon him so that we can move on as a country and no longer talk about him."

Christie has roundly criticized Haley for this wishy-washiness. Just this week (before he announced he was suspending his campaign), Christie said at a town hall: "I would be happy to get out of the way for someone who is actually running against Trump." That is not exactly a full-throated endorsement of Nikki Haley, obviously.

But whether it comes in a formal statement or not, Christie has now essentially endorsed Haley. And his supporters really have nowhere else to go, unless they want to waste their vote on Asa Hutchinson (who, for some inexplicable reason, has not dropped out himself), or just stay home and not vote.

I realize things don't work out quite this perfectly in real life, but the standard pundit way to look at things is to just add Christie's support to Haley's. In Iowa, this won't boost Haley anywhere near enough to actually beat Trump, but it could easily boost her enough to come in second. And if Haley comes in second, DeSantis will be heavily pressured to get out of the race and further clear the path for Haley to take on Trump directly. There are already rumors of his campaign's imminent death, and a third-place finish in Iowa would amplify them enormously. DeSantis had a mountain of campaign cash when he started, and he has put most of his chips on winning Iowa, so this would be a real death-blow to his chances in general.

The next step is going to be even more interesting, no matter what happens in Iowa. Because a week later, New Hampshire votes. And New Hampshire is polling quite differently than Iowa. New Hampshire GOP voters are a different breed of cat from not just Iowa but the nationwide Republican electorate. Chris Christie knew this and put all of his chips on winning the state, from the very start. And he's made significant inroads -- he's handily beating DeSantis in the polling, and has been pretty solidly in third place for the whole race (although he was in fourth for one period, where DeSantis saw his star fall while Haley saw hers rise). Christie is pulling in a consistent 12 points in New Hampshire, which is a much bigger slice of the electorate than in Iowa.

New Hampshire is Haley's best (and possibly last) chance to actually beat Donald Trump. Trump has never been as popular in the Granite State as he is elsewhere, and if the electorate has limited choices they could conceivably push Haley over the finish line. There have been two polls released in January, but they have a pretty wide swing in the gap between Trump and Haley. The first showed Trump at 46 percent with Haley at 26 (a 20-point gap), while the second showed Trump at 39 percent and Haley at an impressive 32 percent -- only seven points away from Trump. If you add Christie's support to the first poll, it means Haley would be solidly in second place, but still lose to Trump by eight points. If the other poll is more accurate, though, Haley could beat Trump by five points. The truth is likely somewhere in between, which certainly gives Haley a fighting chance to actually score the big upset.

What would the effect of DeSantis dropping out be, though? In New Hampshire, DeSantis is only polling at an average of six percent (his actual numbers: eight points in that first poll, and five points in the second). So where would his New Hampshire voters go, if Haley and Trump are the only real choices left on the ballot? Perhaps some of them would migrate to Ramaswamy, but given the choice between Trump and Haley it is really impossible to predict which way they'd break. Do they support DeSantis for his Trumpiness to the extent of defaulting to Trump if he's not an option? That's really the safe bet, at this point. Or are they at the point where no matter how much they may have liked him previously they simply cannot support Trump any longer? It's impossible to know, really.

But what all of this means, really, is that the 2024 GOP primaries could actually wind up not being a repeat of 2016. The field is clearing. If it clears further by New Hampshire, Trump could conceivably lose the state. And if Trump lost New Hampshire and the race was truly a two-person race, what would happen next? The next state to vote would be South Carolina -- Haley's home state. Currently, Trump holds a commanding lead over her there, but if he suddenly appeared weak and beatable, could that conceivably change?

Chris Christie, to his credit, realized all this. He knows that he doesn't have a prayer of actually winning the nomination, and all throughout his campaign he promised that he wouldn't just "be a spoiler" who wound up handing the nomination to Trump. He has now made good on that promise. With the anti-Trump coalition coalescing around Haley's candidacy, Christie knew that if he had stayed in until New Hampshire voted he might well deny her the only shot she's got at mounting a real and viable challenge to Trump. Christie's not exactly a huge fan of Haley, but at least she knows that some Trump policies are beyond the pale. She's a lot more sane than any of the rest of them, to put this another way. So by default, Christie had to help her have her one shot or be called exactly what he swore he wouldn't become -- the 2024 GOP spoiler who handed the nomination to Donald Trump.

If Haley manages to top DeSantis in Iowa and DeSantis reacts by dropping out, then it will indeed be a two-person race heading into New Hampshire. And who knows what that would mean? Trump has even recently agreed to the concept of debating Haley, if it truly were a one-on-one race, so we might even get to see Trump on a debate stage as early as next week.

Chris Christie shook up the race by entering it. He shook up the race throughout, by being unafraid to call Donald Trump exactly what he is. He was unafraid to taunt Trump and call him the same sort of playground insults that Trump uses for everyone else. And, true to his theme to the very end, Chris Christie has shaken up the race to a dramatic degree by his exit.

-- Chris Weigant

Follow Chris on Twitter: @ChrisWeigant