So help me, I cannot remember the last time a leading major-party presidential candidate has stoked so much fear among those within the very party he wants to lead into the next election.

Donald J. Trump’s emergence from the ranks of unthinkable presidential nominee to a possible nominee has been a sight to behold — not that I have enjoyed beholding it.

Fellow Republican, U.S. Sen. Lindsey Graham of South Carolina, has tossed out an idea that (a) won’t go anywhere but (b) has some within the party actually considering it.

Ticket formation could come early.

Graham suggests that Ohio Gov. John Kasich and U.S. Sen. Marco Rubio of Florida ought to declare themselves a “ticket” to head off a Trump nomination. Graham — once a presidential candidate himself — doesn’t care which of them would head the ticket. He just wants two of the remaining five GOP presidential candidates to form an alliance to blunt the Trump charge.

There have been other “insurgencies,” to be sure.

Did the Democrats conspire against the candidacy of Sen. Eugene McCarthy and then Sen. Robert F. Kennedy when they challenged President Johnson in 1968? What about the 1976 GOP insurgency of former Gov. Ronald Reagan, who sought to wrest the nomination from President Ford?

This is different.

The very idea that the Republican Party could actually nominate someone with Trump’s background — as a reality TV celebrity, real estate mogul, and someone who’s boasted about his sexual exploits with women who were married to other men is sending the GOP “establishment” into apoplectic spasms.

As someone said only recently, the Party of Lincoln is becoming the Party of Trump.

Take a moment. Roll that around for a bit and consider what it really means to a once-great political institution.