Editor’s Note: David Axelrod is CNN’s senior political commentator and host of the podcast “The Axe Files.” He was senior adviser to President Barack Obama and chief strategist for the 2008 and 2012 Obama campaigns. The opinions expressed in this commentary are his.

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Running for president is a very demanding test of a candidate's qualifications, and Donald Trump is failing, writes David Axelrod

He says Trump's stumbles over foreign policy, abortion issue, suggests he isn't prepared for demands of the Oval Office

CNN  — 

In 2011, as the presidential race was gearing up and many were predicting defeat for President Obama, I reminded a reporter, in judging potential opponents, just how exacting the process of running for president can be.

“Presidential campaigns are like MRIs for the soul,” I said. Whoever you are, the process will reveal you. And the deeper you go in the campaign, the more this is true.

Candidates for President of the United States are auditioning for the toughest job on the planet. Every issue that comes to that desk in the Oval Office is fraught and consequential. Every comment a president makes can send armies marching and markets tumbling.

Voters intuitively get this. They watch. They see how the candidates make split-second decisions under the klieg lights and measure how these men and women might deal with the relentless pressures of the presidency.

Issues are important. But command and sure-footedness in critical moments are essential.

Which brings us to Donald Trump’s horrendous week.

Let me first stipulate that Trump has made a monkey of me and many other expert bloviators who predicted his candidacy’s early demise.

Regardless of the plausibility or tastefulness of some of his comments and ideas – no, Mexico is not paying for The Wall and America is not going to betray its values by barring a quarter of the world’s population from our shores – Trump has brilliantly tapped into a wellspring of anger and resentment that is real and powerful.

His primal screams about immigrants, Muslims, China, “political correctness” and the corrupt bargain between special interests and Washington have found an enthusiastic audience among white working-class Americans who feel squeezed by changes in the economy and the country and disdained by elites from the Acela Corridor to Hollywood.

They have rallied to the Strong Man, who scoffs at constitutional niceties and international norms and promises to Make America Great Again. For these voters, tired of nuance and complexity, Trump is the anti-Obama ideal – a guy for whom every problem, from terrorism to stagnant wages, is a nail just waiting to be walloped by a leader who has the strength and guts to pick up the hammer.

For months, Trump was buoyed and intoxicated by the allegiance of this faithful throng, whose support was enough to assure him a string of victories in a large and divided primary field. “I could stand in the middle of Fifth Avenue and shoot somebody and I wouldn’t lose any voters,” he chortled in a strange and revealing moment.

He was helped in his improbable march by the timidity of his opponents and the Republican establishment, who until recently were reluctant to tangle with the tart-tongued Trump, hoping he would simply fade away; and by the insatiable appetite of TV news executives, who quickly realized the outrageous former reality show star was an unexpected ratings bonanza.

In the seeming blink of an eye, Trump was transformed from an insult-slinging sideshow to front-runner who, as of today, is the only candidate who could plausibly capture enough delegates to claim a first-ballot victory when Republicans gather in Cleveland this summer.

Now holy hell is raining down upon him.

That is the nature of the presidential gauntlet. The better you do, the longer you go, the greater the scrutiny. The media analyzes and parses every word with a greater seriousness and intensity when spoken by a likely nominee for president of the United States.

For months, Trump had treated the campaign as his own personal open mic night, commanding the stage with his audacious improvisation. This past week, the process caught up with him.

His blithe assertion that he would encourage Japan and South Korea to develop nuclear arms; his defense of his campaign manager’s alleged strong-arming of a female reporter; and his suggestion, quickly recanted, that women who have abortions should be punished, created a sense of chaos around the candidate. He continued to stumble over the abortion issue all week.

Many analysts suggested that the abortion issue could be the death knell for Trump, who with one ill-considered line touched off a firestorm on both sides of the explosive debate. Trump already had catastrophic problems with women. The latest CNN poll showed that 73% of women voters – including nearly 40% of Republican women – held an unfavorable view of Trump before the abortion tsunami hit.

And pro-life Republicans, suspicious of Trump as a late convert to the cause, saw Trump’s lurching back and forth on the issue as yet another sign of his ideological promiscuousness.

But the real damage is more profound.

In the last week, under a front-runner’s scrutiny and pressure, Trump looked like a guy who simply can’t hack it.

This is unlikely to shake off the Trump zealots, that 35% of the Republican primary base who seem unshakably committed. But it could cost him the ability to grow, putting Sen. Ted Cruz and Gov. John Kasich in a position to deny Trump the more than 50% of remaining pledged delegates he needs to clinch the party’s nod.

Even if Trump were to grind out the nomination, which he still may, given his lead, he would enter the general election with significantly lower public approval ratings than any major party nominee in U.S. history, relieving likely Democratic nominee Hillary Clinton of that dubious distinction.

This week, the MRI of Trump’s soul, and of his preparedness to serve as president and commander in chief, began to come into sharper focus.

And while his loyal base may have been unbothered, much of the rest of America was alarmed at what it showed.

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