There have been eight candidate debates to date: five on the GOP side and three for the Democrats. But the get-togethers this week will be infused with an edge, urgency -- even desperation -- we haven't seen in the preseason.
With just weeks before actual voters begin to have their say, there is no time for mild chastisements or subtle jibes. The rapiers and stilettos were fine for '15. Blunt force will be all the rage when the debate season resumes.
The bromance is over. After months of peace and love between them, Donald Trump has turned his relentless fire on Ted Cruz, whose strategic focus on evangelicals has made him the favorite in Iowa, where social conservatives dominate the caucuses. Cruz may be the most serious obstacle in The Donald's path, so Trump has unloaded a blast of Birtherism on the Canadian-born Cruz, hoping to drive a wedge between him and the nativist base they share.
To date, the two front-running mavericks have steered clear of debate attacks against each other, even when invited. Cruz, in particular, has refused to take the bait, bathing his fellow disrupter in bonhomie.
Given the closeness of the public polls in Iowa between the two, it will be interesting to see if Trump will pull his punches when they are once again standing together on a debate stage Thursday or challenge Cruz directly on his constitutional qualifications to serve. And if Trump goes full birther, how will Cruz counter?
The wily Texan, who in his short tenure in Washington has managed to forge a rare, bipartisan consensus among Republicans and Democrats who have come to utterly despise him, has proven surprisingly agile and clever on the campaign trail. Jokes or jibes, dealing with The Donald, however, is a trickier piece of business.
The real fireworks
But the real fireworks on the Republican side may be between the candidates fighting for survival in the narrowing establishment lane. Sen. Marco Rubio of Florida is polling the strongest among them and has emerged as the latest, last best hope of center-right establishment Republicans who see a Trump or Cruz candidacy as a looming disaster.
But Rubio is yet to be tested. Doubts linger about his organization. And he, among all the candidates, has glibly and gamely tried to navigate the three major factions of the party: the populist tea party, evangelicals and the establishment. This has made him broadly popular in a party in which the divides seem unbridgeable.
Look for the other establishment contenders who are banking on New Hampshire -- Govs. Chris Christie and John Kasich, and onetime front-runner Jeb Bush -- to try to slow Rubio down, portraying him as a silver-tongued but callow poseur, too green to govern and too slick by half. Cruz, fighting off any incursions among his base, may join in, as he and Rubio have been sniping at each other for weeks, with Rubio accusing Cruz of being weak on defense and Cruz flaying Rubio for collaborating with the enemy (Democrats) on immigration.
For Christie, the New Jersey governor who has spent much of the last year in New Hampshire seeking a new start after scandals at home badly tarnished his image, the next debate may require a departure in strategy.
Previously, the beefy former prosecutor has saved his Sopranos-style salvos for Clinton and President Obama, chastising his GOP opponents for their intramural squabbling. But with time short and New Hampshire do or die for his candidacy, Christie lately has been exchanging fire with Rubio in interviews and on the air in a brawl likely to spill onto the debate stage Thursday.
This battle within the GOP establishment lane, narrowed as it apparently is, will have huge consequences.
If Rubio finishes ahead of the establishment pack in Iowa and New Hampshire, he will advance, along with Trump and Cruz, in what could quickly become a three-way battle for the nomination.
But that is far from guaranteed. The average of the most recent polls shows just four points separating the four leading establishment contenders. Rubio is under fire from multiple directions, and he and his allies have placed a huge TV buy in New Hampshire to ward off the attacks.
And if one or more of the other establishment candidates edges Rubio -- particularly in more centrist New Hampshire, where they all are staking their claims -- the field may remain larger for longer, a development that could help Trump, with his consistent 35-40% share of the vote.
All this guarantees a tart and tense debate with Rubio the focus of attention, though the last-minute demotion of Sen. Rand Paul to a junior debate (in which he declined to participate) for poor poll numbers was good news for Rubio, who was one of Paul's favorite targets.
Here's the outlook for the Democrats:
Hillary Clinton's surprisingly strong rival
Hillary Clinton continues to be the presumptive Democratic nominee, but the presumption is being strained by heated races in the first two states.
Bernie Sanders has run surprisingly stubborn campaigns in Iowa and New Hampshire, threatening to hand Clinton a pair of defeats to open the voting season.
Clinton, who has huge advantages and polling leads in subsequent states, would still be a heavy favorite. But if Sanders were to upend her in Iowa, far from his Northeastern base, the race is sure to drag on longer and provoke new questions about Clinton's perceived vulnerabilities.
Wary of such an unwelcome scenario, the former secretary of state, who once trained her sights only on the GOP, has engaged Sanders in recent days, focusing on two of his vulnerabilities in the Democratic race: His mixed record on gun control and the fear among voters who like them both that a 74-year-old, self-styled Democratic Socialist cannot win in the fall.
The Clinton campaign has begun airing a clever ad featuring provocative snippets of Trump, Cruz and the GOPers, and concluding that only Clinton can stop them. The subtext to wavering Democrats: Vote with your head, not your heart; Sanders equals a Trump-led America.
Wall Street apparatchik?
Sanders, in turn, has stepped up his own fire, painting Clinton as a Wall Street apparatchik, too mortgaged to the bankers and corporate interests to bring about real change. (Vice President Joe Biden added a log to that fire, opining during a CNN interview Tuesday that Clinton was relatively new to the issue of inequality.)
The Vermont senator is also brandishing poll numbers showing him doing better against the leading Republicans than HRC, though such numbers 11 months out are not all that predictive. Unlike the more numerous Republican debates, the few Democratic debates have been noteworthy for the broad areas of agreement between Clinton, Sanders and former Gov. Martin O'Malley, who is languishing in low single-digits despite his earnest and energetic efforts and appears headed for the sidelines.
Sanders bailed Clinton out of a pointed question on the email controversy that dogged her earlier in the year and has generally shown deference when given the chance to bore in. Clinton generally has responded in kind. As both are well-liked among Democrats, there was little point in sparring.
But with the clock ticking down and his numbers ticking up, Sanders can expect rougher treatment in Sunday's debate and will have to decide how hard to hit back.
On both sides, January promises to be a cruel month, as ambitions collide in the frigid snows of Iowa and New Hampshire.