Donald Trump hinting at a Hillary Clinton assassination isn't the last straw – his campaign is already over

The pattern is unvarying. At the urging of his advisers, Donald Trump gets presidential. He consents to employ the despised teleprompter, like other politicians, and delivers a prepared text. Donald wouldn’t be Donald, of course, without a bit of ad-libbing. But the add-ons are kept under control, and the reviews are OK. Then all the good work is undone.

Back to the rallies, the unscripted speeches and the intoxicating roar of the crowd; back to the bright lights of the TV studio or the impromptu chat show call-in; and back to that irresistible little blue bird called Twitter. And it’s off to the races again.

It happened at the Republican convention. Trump delivered his prepared acceptance speech. You may disagree with the dismal picture it painted of the US, but it was on message, barring perhaps the assertion that “I alone” can fix the country’s problems.

But within days the good work was undone. He insulted Muslim American parents who had lost their son, a captain in the US army, in the Iraq War; he refused to endorse the Republican speaker of the House, his party’s most senior elected official, for a primary; and he committed various other blunders I’ve now forgotten – you just can’t keep up with them all.

The result? Sliding poll numbers, advisers tearing their hair out and desperate pleas for another campaign reboot. So it’s back to the teleprompter, this time for Monday’s big economic speech in Detroit.

The economy is an area where Trump may have the edge on Hillary Clinton and the reviews of his performance are OK. But, again, back to the crowds and Trump messes up again, this time saying that if Hillary gets elected and appoints Supreme Court judges who are anti-gun rights, “Then nothing you can do folks…although the Second Amendment people – maybe there is, I don’t know.”

Yes, it’s ambiguous. Maybe it’s another deadpan Trump joke. But given the sheer hatred of Hillary that permeates his rallies, their violent undertows, and the number of nuts out there with AK-15s, America shivered a little.

Is this the straw that breaks the camel’s back? Probably not. To mix metaphors, his presidential bid is dying by a thousand, mostly self-inflicted, cuts. Amid and obscured by the gun fuss, 50 top Republican national security officials publicly disowned Trump – as did Susan Collins, a Republican senator from Maine – all of them saying he is reckless and temperamentally unfit for the job.

The truth is that Trump is in way over his head. What worked in the Republican primaries, where playing to the base was all, isn’t working now.

Trump can’t change his message to expand the base. In fact, he can’t change, period. November 8 is still almost three months off but barring some deus ex machina – a bombshell Clinton email hacked by the Russians? – the outcome is pre-ordained.

Hillary is a lucky lady. She’s a flawed and stale candidate who continues to peddle legalistic half-truths over those State Department emails. But thanks to Trump’s excesses, no one notices. A lucky lady indeed. Unless, of course, some gun nut gets to her.