Michael Barone, in a WSJ op-ed Friday, puts the Trump phenomenon in historical context:
Even if Donald Trump secures the Republican nomination and somehow overcomes current polls to be elected president, there will be few Trump clones among Republicans in Congress and in state and local office.
If he is nominated and defeated by a wide margin, he will not leave behind a Trumpist movement with the popular and intellectual depth of the conservative movement following Goldwater’s defeat 52 years ago—his legacy may be little more than an impulse toward opposition to trade agreements and legalization of illegal immigrants. If he is not nominated and tries to run as an independent, he will not have the support of as significant a third-party apparatus as Theodore Roosevelt did 104 years ago.
As this is written, it seems likely but not certain that Mr. Trump will fall visibly short of the 1,237-delegate majority, and that he will inflict significant damage on the Republican Party by protests or perhaps an independent candidacy. But probably nothing like the serious, though temporary, damage inflicted by that vastly more talented, experienced and intellectually serious disruptive New Yorker, Theodore Roosevelt.