In the space of 96 hours, at least four Republican elected officials — Sens. John Thune (S.D.) and Deb Fischer (Neb.), as well as Reps. Bradley Byrne (Ala.) and Scott Garrett (N.J.) — went from condemning Donald Trump and insisting that he should step aside as the party's presidential nominee to acknowledging that they planned to support the GOP ticket.

Take Thune is a member of the Senate Republican leadership and someone regularly mentioned as a potential national candidate. On Saturday, he tweeted that Trump should "withdraw." On Tuesday, Thune told a local station that "he plans to check all the boxes of Republicans on his ballot."

Um, what?

The whiplash caused by such flip-floppery is striking. And it is evidence of a broader issue within the Republican Party that Trump has pushed to the fore with his damn-the-torpedoes campaign: The party establishment and the party base are further apart than perhaps ever before — and elected officials live in fear of getting on the wrong side of their activist base.

A gap between the political views of the party establishment and the party base is neither new nor unique to the Republican Party. Party bases are by definition more extreme in their beliefs than are the men and women they send to Washington to represent them. It's a constant push-pull; the base tries to move the party further to the partisan poles while its elected officials, traditionally, work to moderate it — driven by the desire to find compromise.

But, in the past six years or so, the Republican Party base had become increasingly radicalized. And the party establishment has been very slow to realize just how far away its beliefs are from the base voters on whom they have long depended for support.

The signs have been there for some time. In 2010, Sen. Bob Bennett (Utah) lost badly at a nominating convention amid a conservative uprising. Legendary (in Washington) Sen. Richard G. Lugar (Ind.) lost a 2012 primary to a little-known challenger backed by the tea party. Two years later Eric Cantor (Va.), at the time the second-ranking Republican in House leadership, lost to a total unknown named Dave Brat in a Republican primary.

Those losses began to wake the establishment up to the threat posed by the GOP base. Crossing the base, it was now clear, could be a very dangerous proposition. (Another key to this sea change was the rise of well-funded super PACs fueled by donations from decidedly conservative major donors.)

Trump became the full realization of how powerful the party base had become and just how much that base disdained the people ostensibly elected to lead it. Trump's entire candidacy was premised on the idea that Republican leaders had sold out the voters who put them there — that these "leaders" were dumb and had cut bad deals. He, an outsider to politics who owed nothing to anyone, was the only one who could change it.

It speaks to how ivory-towered the party establishment was that, despite the losses of Lugar, Bennett and others, it assumed the 2016 presidential election would be immune from those prevailing winds. Sure, it happened at the House and the Senate level, but this was the presidential nomination we were talking about! Surely, common sense would prevail!

Then Trump romped to the nomination, crushing establishment favorites Jeb Bush, Marco Rubio, Scott Walker and John Kasich. It speaks to the power of the base and the disconnect between the base and Republican elected officials that the final two contenders for the GOP nod were Trump, a candidate little regarded by Washington Republicans, and Ted Cruz, a candidate widely hated by those same Republicans.

Trump's rise finally made the party establishment types realize that they were the emperor with no clothes. They weren't leading the party, they were being led by it. The people they had always taken for granted had suddenly realized that, when unified, they had lots and lots of power. The jig, as it were, was up.

Faced with an angry political mob at their doorstep, politicians did what they have always done: They focused on self-preservation. That's what's behind the series of flip-flops that the likes of Thune, Fischer and others have undertaken over the past few days. It's also at the root of why people such as Sen. Kelly Ayotte (N.H.) have struggled so mightily to deal with Trump in their own races.

On the one hand, they dislike him personally and believe that what he is doing is detrimental not only to their own political futures but to the overall well-being of the Republican Party. On the other, they are desperately afraid of being cast as insufficiently loyal to the party, of being known forevermore as RINOs (Republicans in Name Only), of losing.

In the fight between personal belief and political calculation, the latter almost always emerges the victor. That's what's happening all across the Republican establishment these days as its elected leaders run scared from a base they fear will come for them next.