This post will be my version of a "live" blog on tonight's results. Thirty minutes of writing, minimal editing, a few short points. Apologies in advance for any typos, etc.
1. Marco Rubio had the most riding on tonight. Finish a strong 2nd, and he could have consolidated establishment support in a 3 way race, and would have been the likely Republican nominee. Instead, however, his nightmare scenario is unfolding.
With 75% of the vote in, he looks likely to narrowly finish fifth. In one quick flash, his path to the nomination became highly murky. With John Kasich finishing 2nd, and Jeb Bush finishing either 3rd or 4th, neither is likely to drop out of the race. Especially in light of Rubio's disastrous debate performance on Saturday night, establishment Republicans who might have favored his electability may now give Kasich and Bush another look.
Simultaneously, however, Rubio is stuck as the 2nd choice for rock-ribbed conservatives. Many conservative commentators, including Rush Limbaugh, the king of conservative media, have spoken up for Rubio after his debate debacle, reminding viewers, listeners and readers that while his delivery was poor, his point—that President Obama deliberately aims to transform the country—is correct. Yet, conservatives still favor the purer and more bellicose Ted Cruz, who has also outperformed Rubio twice now.
This situation leaves Rubio blocked in both the establishment and conservative lanes, and it's hard to see how he emerges and where he might win a state.
2. Conventional wisdom will dictate that Cruz and New Hampshire winner Donald Trump will now engage in a bloodbath in South Carolina, trying to tear each other from limb to limb, as they brawl it out at the top of the Republican pack. In my view, Cruz should resist this temptation and focus on ending Rubio's campaign.
If he spends his time and money attacking Rubio, Cruz might be able to drive the Florida senator from the race. Do that, and Cruz basically consolidates all of the conservative vote (it's hard to see the hapless, but gentlemanly, Ben Carson soldiering on much past South Carolina, if he lasts that long). With conservatives unified, Cruz can then rely on a superior ground game and start duking it out with Trump in the "SEC" primary on Super Tuesday (dubbed that because of the many Southern states holding elections on that day).
This scenario would allow Cruz to avoid worrying about being hit on both flanks. Leave Rubio wounded, but alive, and he remains there to peel off votes if Cruz falters, and peskily nip at the Texas senator's heels.
3. Tonight increases the still low odds of an open Republican convention where no one has enough delegates to secure the nomination going in. It seems likely that tonight's results will keep at least a 5 way race going through at least the aforementioned "SEC" primary. Many of the states in play on March 1st have winner take all systems.
That means that someone could win all of a state's delegates with a relatively small share of the vote. The more ways that the electoral votes fragments, the greater the likelihood that the race never consolidates and no one ends up with a majority of delegates in advance of the convention.
4. Bernie Sanders seems to be stitching together an interesting coalition—he won 72% of independents, and whopping percentages of millennials. He also won a majority of moderates. That might indicate that his coalition consists of both idealistic young voters who are drawn to Sanders policy prescriptions AND independents/moderates turned off by Hillary Clinton's ethical baggage. These voters may not love Sanders' policy prescriptions, but they have nowhere else to turn.
5. If Clinton sees her poll numbers start to erode in South Carolina (where, for the first time this election cycle, the electorate will not be almost entirely white) it may be time for her to go sharply negative on Sanders. She has to convince the young voters drawn to the Vermont senator that, ideal though his policy prescriptions may be, they will also be enormously expensive. Clinton must convey to these voters that they (and their parents) will pay for these policies through sharply higher taxes.
If Clinton's polling holds in South Carolina, however, she can eschew this sort of tactic, and instead breathe easier as we move from the retail phase of the campaign to the phase in which her superior campaign organization should help her. She also should do better as the campaign moves away from caucus states and New England—both of which lean towards Sanders, because of his passionate base and his New England roots.
Bonus thought: the true winner tonight? The media. Colorful candidates, a total free-for-all on the Republican side, a Democratic race that will advance far longer than anyone expected, and endless scenarios to discuss.