ANALYSIS: Paul Ryan Battling Trump for Soul of GOP

Donald Trump has used tweets to insult women and ethnic groups, and to drive news cycles over everything from his late-night TV choices to his midday food options.

But he escalated his feud this morning with House Speaker Paul Ryan in a profound way, with implications and ramifications that extend far beyond November.

"Paul Ryan said that I inherited something very special, the Republican Party," Trump wrote on Twitter. "Wrong, I didn't inherit it, I won it with millions of voters!"

On a basic level, Trump is right. He stands now as the presumptive Republican presidential nominee because of millions of the Republican Party's own voters, and in spite of, almost to a man and woman, the party's leadership.

Many or most of those who matured under traditional conservative ideas, shaped by opinion-makers and even presidents, have never been able to accept the idea of Trump as the nominee because he gave so little care to what they have considered core to the party's ideals.

But that's where Ryan and a handful of other prominent Republicans come in. The speaker's unusual decision to hedge on his support for Trump at this moment - to declare that earning millions of more votes than any other candidate isn't enough to earn the support of the Republican speaker of the people's House - is a move that will be felt for years, perhaps decades.

"This is the party of Lincoln, of Reagan, of Jack Kemp," Ryan told CNN's Jake Tapper Thursday. "What a lot of Republicans want to see is that we have a standard bearer that bears our standards."

Nebraska Sen. Ben Sasse, a freshman Republican who has been compared to Ryan, went even further in a Facebook posting less than 24 hours earlier. Sasse has declared that the conservative thing to do is to reject the Republican nominee and draft a third-party candidate with a commitment to conservative principles.

"This is America. If both choices stink, we reject them and go bigger. That's what we do," he wrote. "Remember: our Founders didn't want entrenched political parties. So why should we accept this terrible choice?"

A third-party option seems increasingly unlikely to materialize. Fast-approaching ballot deadlines and the strong probability that such a move would lead directly to a Hillary Clinton presidency are choking off those options, even if a perfectly positioned candidate existed.

But the fact that such discussions are even happening marks an extraordinary moment in a country that has seen party ideology defined from the top down for as long as anyone in politics has been alive.

Trump usurped a power structure that has been dominant for at least a century. Even the famously disciplined Republican Party is too shaken to accept that he won, by playing by the rules that Trump has consistently, and accurately, described as rigged in favor of party leaders.

Ryan did not rule out supporting Trump down the line. Republican National Committee Chairman Reince Priebus, who has sought to unify the party behind its soon-to-be nominee after months of coming under pressure to resist him, said today that he's confident Ryan and other holdouts will come on board.

In the immediate term, Ryan's move gives cover to other Republicans who are in or are seeking office to distance themselves from Trump and the offense and outrage he generates. It also guarantees that the opposition to Trump will not emanate only from loud and angry voices in the GOP, ensuring an ugly presidential race that seems likely to tip to the Democrats.

Trump's candidacy represents a policy threat to what Republicans have stood by for generations. His is a populist and nativist vision, resisting and seeking to reverse what previous Republican presidents have sought to accomplish on trade, taxes, immigration and foreign policy, just for starters.

To their frustration, the election will almost certainly be a choice between two options many conservatives view as simply bad. Many will say it's a choice they can't make and, yes, that will hurt Trump in November.

But by seeking to reclaim principles at this political moment, Ryan and some of his allies are seeking to make this election more than a binary choice. That may not be good for the Republican nominee of 2016, but it may be what the Republican Party, and even the two-party system as we know it, needs to survive beyond that.