We've had the First in the Nation and Super Tuesday. Call this the GOP's Titanic Tuesday: They're either going to hit the iceberg known as Trump, or not.

As you probably know by now, much rests on the outcome in Tuesday's primaries, the first under GOP rules that allow states to award all of their delegates to the winner. Two of the four remaining candidates are making last-ditch efforts to save their campaigns in their home states: John Kasich in Ohio and Marco Rubio in Florida. So the results will either renew their hopes or bring the race to a final two of Donald Trump and Ted Cruz ... or something in between.

Charlie Harper at GeorgiaPol.com (and formerly of Peach Pundit)  has a good breakdown of the mathematical possibilities that I won't repeat here. Suffice it to say, a Trump sweep of winner-take-all Ohio and Florida would make him the presumptive nominee, a Trump oh-fer in those states would put Republicans on the fast track to a contested convention, and a split would leave the picture a bit cloudy.

If the GOP is going to avoid nominating Trump, Tuesday's results are paramount. A contested convention between two near-equals (presumably, Trump and Cruz) could legitimately end with either man as the nominee. A contested convention with Trump barely short of a majority and Cruz trying to cobble together everyone else to reach a skinny majority would only end in a party schism, although I'm not sure that's truly avoidable at this point.

That's been the conventional wisdom for a couple of weeks now. What's interesting is how the states other than Florida and Ohio have become so crucial. The limited polling we have in Illinois, Missouri and North Carolina suggests we could see tight races in those three, the first two of which are also winner-take-all. Illinois actually has a few more delegates than Ohio, as does North Carolina. The Cruz campaign has been focused on that trio of late, which could more than offset a Trump victory in Florida.

All of which is to say: Don't turn off the TV after Florida and Ohio report. There's a lot to watch tonight. I'll post an update as the results warrant.