Of all the bits of conventional wisdom floating about in the political environment, perhaps the most enduring is that which holds when the national economy is solid, the incumbent Administration wins re-election.

There exists ample historical evidence that, other than in times of global warfare, Americans vote their self-interest, reflecting comfort in their economic circumstance and optimism that it will continue.

Not surprisingly, the White House occupant — regardless of party — reaps the benefit of a nation grateful for low unemployment, rising wages, job opportunities, a robust stock market, low interest rates, and a sense of confidence in the future.

As President Trump ramps up his re-election effort, the economic well-being argument that translates into popular support tilts in his favor.  Growth has accelerated in his 32 months in office and each employment report seems rosier than the one before.

Why, then, is he doing everything in his power to dilute the message while careening off into other directions, needlessly creating controversy and uproar?

The answer seems to be that it’s in his nature, that he’s incapable of passing up any opportunity to verbally firebomb his critics or to throw himself behind bizarre or totally unworkable ideas.

His continued assaults on four first term Congresswomen — collectively dubbed “the squad” — is pointless, thoroughly without any political benefit while contributing to a growing sense of his darker racially-motivated impulses.   Engaging with the four only serves to elevate them and give them the attention they crave while diminishing him.

He’s repeatedly demonized immigrants, attributing criminal behavior to them, suggesting they are flooding the nation in search of taxpayer-supported social services and will steal jobs from American citizens.

His “let’s buy Greenland” (pictured, above) from Denmark idea, presumably hatched on a slow day in the oval office, portrayed a chief executive who’s detached from reality musings suddenly became public policy.

Picking a fight with the prime minister of Denmark?  Really?

With the mass shootings in El Paso, Texas, and Dayton, Ohio, still tragically fresh in the public mind, the president swung to and fro on the matter of implementing universal background checks for gun purchasers, producing a thoroughly muddled Administration position and a Congress uncertain of what he’d support.

It suggests, further, that the National Rifle Association has succeeded once again in bending the Administration to its will.

He relishes the confrontation with China over imposing higher tariffs on imports, boasting that he’s been chosen by some higher authority to take on the fight because no one else possesses the courage to do it.

In the meantime, American farmers in particular are paying a stiff and potentially ruinous economic price for the trade conflict.

Politicians and candidates are urged to relentlessly stay on message, to play to their strengths while avoiding the kind of political entanglements which distract from a smooth, coherent narrative of competent stewardship and effective leadership.

Trump, it appears, is incapable of accepting that advice, much less following it.

He’s convinced he’s his own best strategist, policy maven, press secretary and political genius.  His staff is often caught flat-footed by his off the cuff pronouncements, leaving them to scramble to clarify his views and sweep up the rubble left in his wake.

His relationship with the media is arguably the worst in the history of representative government. It is no longer merely a difference over coverage; it’s escalated steadily to an unprecedented level of hostility and animosity, reaching a point at which interactions no longer involve questions and answers, but have become arguments usually heard in local pubs around closing time.

In no other Administration in history has there occurred the appalling spectacle of an ex-White House adviser angrily confronting a reporter in the Rose Garden and having to be separated by a Secret Service agent before it turned physical.

Trump, his confidantes are quick to point out, does not take criticism well and, when hit, strikes back twice as hard.

The American people, they contend, were well aware of the Trump personality and style when they elected him in 2016 and there should be no sudden surprised reactions when it turned out that he behaved as president the same way he conducted himself in the dog eat dog world of New York real estate development.

He is unique and unorthodox, but the lack of discipline and focus combined with a stubbornness that he is right and his critics wrong — no matter the issue — has taken a toll.

His public approval is mired in the low 40’s range; he trails the top five Democratic presidential candidates in head to head matchups, and a significant plurality of voters believe the country is headed in the wrong direction.

By failing to concentrate on the health and growth of the economy and emphasize that his policies made it all possible, Trump may have marched to the edge of the abyss.

Instead of reminding Americans at every opportunity that his business shrewdness and insight have produced a rock solid economic foundation and that a second term would build upon that success, he chose to engage in fights and arguments which diminished himself and gave his foes repeated openings to cast doubt on his intellectual powers as well as his temperament.

That conventional wisdom concerning economic contentment as the key to political and electoral success has survived numerous upheavals and always emerged undisputed. (Recall “It’s the economy, stupid,” the 1992 Clinton slogan that’s forever embedded in campaign lore.)

Trump’s failure or refusal to grasp that concept and his advisers’ inability to convince him otherwise may well prove to be his undoing.

He may yet be rescued by an unruly band of Democratic presidential candidates each intent on demonstrating he or she is further to the left on the ideological scale than the others.

Gambling his success on the other party’s potential for self-immolation is risky in the extreme.

Sticking with taking credit for a strong economy is both easy and certain.

Carl Golden is a senior contributing analyst with the William J. Hughes Center for Public Policy at Stockton University.