Well, that happened.

In a presidential cycle of history-making firsts, we have now had the first candidate ever to brag about the size of his, ahem, presidential timber on a debate stage.

“I guarantee you there’s no problem. I guarantee you,” Donald Trump said to dispel any thought that all this talk about his small hands meant that “something else” was small as well.

Not that it matters particularly in a presidential cycle that has seen more insults, more putdowns, more small-mindedness, and more trolling than every previous primary season combined.

The saying favored by British Prime Minister Winston Churchill was, “When you’re going through hell, keep going.” But for Republican voters, it just keeps going and going and going …

The reasonable question for the GOP now is what chances remain to defeat Hillary Clinton, the presumptive Democratic nominee. As we know, party unity is the perhaps most important asset either side can take into a general election, and Republicans are way past the point of disunity.

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It will, of course, matter how the nominating process ends. The two paths forward for the Republicans involve either Trump becoming inevitable eleven days from now with knockout wins in Florida and Ohio or, alternately, five rugged months of state-by-state fighting followed by a contested convention.

As for the first possibility of the quick Trump victory, Thursday’s debate showed important signs of a shift. None of the other candidates on stage took even passing shots at one another. Every attack was aimed at Trump.

You can call it the start of the Romney Plan. Earlier in the day, the 2012 Republican nominee laid out an indictment of Trump as a candidate who could not win a general election, and who, if he did, would still be an unacceptable commander-in-chief.

But Mitt Romney also laid out a strategy for his party. Romney said that as a voter he would choose whichever candidate in his state had the best chance of defeating Trump.

That means Marco Rubio in his native Florida, John Kasich in Ohio, where he serves as governor, and perhaps Ted Cruz in Michigan where evangelical voters are a powerful force in the western part of the state. And it also means the candidates can’t attack each other on stage or in their priority states.

The Romney Plan certainly seemed to be in effect here. And since earlier in the day, John Kasich associated himself with Romney’s thorough thrashing of Trump, there’s reason to think that he might tacitly be on board.

But will all that matter?

Next week’s contest here in Michigan as well as Idaho and Mississippi will start to tell the tale.

For Republican voters, however, who watched mouths agape at locker room talk from their frontrunner, and a series of brutal attacks on his record and character from his opponents, despair is setting in.

Much of the fight on the Republican side is centered on who can beat Clinton. The growing fear among GOP voters is that the answer might be: “None of them.”

[GOP delegate count: Trump 319; Cruz 226; Rubio 110; Kasich 25; Carson 8 (1,237 needed to win)]

Chris Stirewalt is digital politics editor for Fox News. Want FOX News First in your inbox every day? Sign up here.

Chris Stirewalt joined Fox News Channel (FNC) in July of 2010 and serves as digital politics editor based in Washington, D.C.  Additionally, he authors the daily "Fox News First" political news note and hosts "Power Play," a feature video series, on FoxNews.com. Stirewalt makes frequent appearances on the network, including "The Kelly File," "Special Report with Bret Baier," and "Fox News Sunday with Chris Wallace."  He also provides expert political analysis for Fox News coverage of state, congressional and presidential elections.