Donald Trump is a legitimate president. Sure, there are many questions about the way the election was conducted last fall, and he did lose the popular vote. But he clearly won under the Electoral College system, and the office -- if not the man -- deserves respect.

There is a more important question hanging over Trump's inauguration, however: Does he have the judgment, temperament and self-discipline necessary to be an effective leader? If legitimacy is a settled issue, ability is not. And so far, the evidence has not been encouraging.

Since the election, Trump has plunged into various battles with actress Meryl Streep, the casts of "Hamilton" and "Saturday Night Live" (again!), Rep. John Lewis, CIA director John Brennan, the entire intelligence community, many European leaders, and news outlets CNN and Buzzfeed.

His behavior is so self-absorbed, so thin-skinned, so lacking in a sense of proportion that only one explanation makes any sense: He cannot help himself. He has to respond to every slight, every criticism, with the rhetorical equivalent of a cruise missile.

That hypersensitivity is the last quality we need in a president. He will be bombarded by critics every single day for the next four years. And he should heed the advice of Barack Obama, who was asked on "60 Minutes" what skills are required to be a good president

"Thick skin helps," answered Obama immediately, and he should know. After all, he was subjected to years of painful accusations that he was not a legitimate president by none other than Donald Trump.

The issue here is not just, well, skin-deep. The most important quality in a president is the ability to make sound decisions in the middle of a crisis. To keep his cool and his calm. To be a source of confidence, encouragement and yes, hope.

In the wonderful documentary by Ken Burns about the Roosevelts, columnist George Will says that when FDR took office in the middle of the Great Depression, his most effective weapon was his smile: jaunty, magnetic, optimistic.

Trump's face is marked by a scowl, not a smile. He seems consumed by grievances, and his campaign was animated by the settling of scores and exploiting the grievances of others. The slogan "Lock her up" was as popular as "Make America Great Again."

Qualms about Trump's personal qualities are not new, and the election did not erase them. Look at these astounding exit poll results: 61 percent of voters said Trump was unqualified to be president, yet 17 percent of those skeptics voted for him anyway. Sixty-three percent said he lacked the temperament to be president, but 19 percent of those chose him over Hillary Clinton. In the latest ABC/Washington Post poll, only 4 in 10 Americans view him favorably or express confidence in his decision-making.

As a candidate, Trump survived those widespread fears about his flaws and failings. But as he takes office, those flaws become far more consequential.

Start with Russia. Trump repeatedly attacked the intelligence agencies for reporting that Moscow had tried to tilt the election in his favor. Finally, grudgingly, he had to admit the charges were accurate.

Then he assailed the intelligence community again, suggesting they had leaked potentially damaging information about him, and made a totally unhinged comparison: "Are we living in Nazi Germany?"

CIA director Brennan firmly rebuked Trump on Fox News for his wild accusations. "There are many dangers" to such undisciplined behavior, said Brennan. "Spontaneity is not something that protects national security interests. And so, therefore, when he speaks, when he reacts ... the implications and the impact on the United States could be profound. It's more than just about Trump ... It's about the United States of America."

With our new president, however, everything is about Trump. Listen to professor Fred Greenstein of Princeton, a leading scholar of the presidency, who evaluated the impact of six qualities on the performance of 12 presidents, from Franklin Roosevelt through George W. Bush.

His conclusion: The single most important characteristic in a successful president is "emotional intelligence" -- the ability to remain "fundamentally free of distracting emotional perturbations." Of the 12 leaders he studied, four were clearly "emotionally handicapped": Lyndon Johnson, Richard Nixon, Jimmy Carter and Bill Clinton. All were crippled by these emotional disabilities.

Greenstein concludes: "Beware the presidential contender who lacks emotional intelligence. In its absence, all else may turn to ashes."

For the good of the nation, we have to hope that Trump's distressing display of "distracting emotional perturbations" does not ruin his presidency.

– Steve and Cokie Roberts, NEA Columnists