WASHINGTON-Firm supporters of Donald Trump will say his suggestion that “the Second Amendment people” could prevent a President Hillary Clinton from appointing a Supreme Court justice favoring gun control was clearly a call to them to vote against her in November.

Some will say it’s just another example of a biased, anti-Trump American news media working their insidious campaign to bring their icon down. They will profess to be aghast at the notion that he might be suggesting that the gun enthusiasts assassinate her, or even unintentionally plant such a horrible notion in anyone’s mind.

But whatever his intention or motivation might have been, the very act of uttering those words should be ample justification for voters, regardless of their feelings toward Hillary Clinton, to conclude at long last that Donald Trump lacks the self-discipline and temperament to be President of the United States.

Trump’s flip comment in that speech in North Carolina was a crystal-clear demonstration that he is an overinflated rabble-rouser with at best a tin ear to the potential influence of his words, whether in this case merely careless or consequentially vicious.

His pointed rallying cry to the wide and loyal army of the gun lobby, led by the National Rifle Association and its sports shooting allies, is certainly in keeping with his modus operandi, which he equates with American patriotism and war cry of “USA!” This year it was a trademark of Trump political rallies long before the Olympic Games in Rio de Janeiro gave voice to its popular shout of national pride.

Trump’s latest shooting from the lip simply adds to the mass of other evidence of his unhinged temperament, most conspicuous in the racial and ethnic slurs and insults with which he kicked off his candidacy.

This behavior has finally begun to stir the responsible remnants of the Republican establishment he thoroughly shattered in his primary campaign of personal vilification earlier in the year.

The futile efforts of those who dared take Trump on then, like 2012 party nominee Mitt Romney and the supposed 2016 Republican frontrunner, former Florida Gov. Jeb Bush, were decimated and humiliated in the process, leaving much of the old GOP a shell.

After the party’s national convention in Cleveland, which only magnified Trump’s deeply divisive influence, capped by his dictator-like declaration that “only I can fix” the nation’s ills, he has entered the general election on a course of self-gratification – but also, increasingly, of self-destruction.

Much too late, some in the discredited party establishment, with the former presidents Bush essentially washing their hands of the fiasco, have begun to push back.

A group of about 50 leading national security experts from Republican administrations going back to the Nixon and Reagan years have written a public letter casting Trump as “lacking the character, values and experience” to lead the country and saying he “would be the most reckless president in American history.”

Fortunately, the Democrats, including Hillary Clinton, have been focusing on the role of the president as commandeer-in-chief of the armed forces and chief architect of American foreign policy. They are questioning Trump’s qualifications in this critical realm and his capability to function level-headedly in it.

Some within the GOP now are even suggesting that Trump should be deposed as the Republican nominee, perhaps through a vote of the Republican National Committee, as party rules allow. But such recourse would only dig the Grand Old Party in an even deeper political hole.

There is also some fanciful wishful thinking afloat that Trump, facing humiliating defeat, might continue to sing his refrain of a “rigged system” and throw in the sponge. But neither his egomaniacal drive nor his near-fanatical followers would likely entertain that outcome.

So the question arises of how Trump and his not-so-merry band of fixers led by old Nixon hand Paul Manafort can extricate him from his post-convention comedy of self-inflicted errors, and make a credible race of it against Hillary Clinton.

Her unfavorability in the polls almost matches Trump’s. As pathetic as it is to ponder, could the presidential race come down to that factor on November 8?

Editor’s note: Jules Witcover’s latest book is “The American Vice Presidency: From Irrelevance to Power,” published by Smithsonian Books.