CNN Opinion asked contributors who have worked in or studied presidential administrations, some with a front row seat, for their take. The opinions expressed in this commentary are solely those of the authors.
Of the many qualities required for presidential leadership, three seem especially important in coming years:
Character: Historian David McCullough argues that character is the single most important quality of a president. That seems true at a time when Americans are so divided and distrustful.
Executive capacity: A president must not only have principles but the ability, vision and courage to put them into action. There is no substitute for past executive experience.
Empathy and appreciation of differences: In a world best characterized as volatile, uncertain, complex and ambiguous, our new President must have an ability to listen and work collaboratively with people of vastly different perspectives.
Historians rank Washington, Lincoln and FDR as our best presidents. Our next must try to walk in their shoes.
David Gergen is a senior political analyst for CNN and has been a White House adviser to four presidents. A graduate of Harvard Law School, he is a professor of public service and co-director of the Center for Public Leadership at the Harvard Kennedy School. Follow him on Twitter: @david_gergen.
Juliette Kayyem: Calm in a storm
I have worked for one governor, two presidents and several Cabinet secretaries, and the attribute that has impressed me the most in times of crisis and homeland security emergencies is the capacity to keep one's cool in the middle of the maelstrom.
It is easy to create scapegoats, increase the temperature and throw red meat at the masses. It is harder to take the long view, to understand that sometimes stuff happens, and that blame and hysteria are a lazy man's low-hanging fruit.
President Obama displayed this attribute during the Ebola crisis; while so many looked to close borders or isolate populations, Obama allowed the science to guide the response, regardless of what the political noise may have been demanding.
Building resiliency while maintaining our values is the true sign of success.
CNN National Security Analyst Juliette Kayyem is a professor at Harvard's Kennedy School, a former assistant secretary of Homeland Security in the Obama administration and founder of Kayyem Solutions, a security consulting firm. She is the host of the "Security Mom" podcast and author of a forthcoming book, "Security Mom: An Unclassified Guide to Protecting Our Homeland and Your Home."
David Axelrod: Nimble and decisive
Having spent two years in the tiny rectangular office next to the big oval one, I got in-depth exposure to the demands of the presidency.
There is nothing like it and, therefore, no experience that can perfectly prepare you for it.
On any given day, a president deals with one complex and consequential problem after another, for which there rarely are easy solutions. Some require immediate action and can arrive in the dead of night.
At any given moment, the president will be asked to comment publicly on breaking issues, knowing that a misplaced answer can send armies marching and markets tumbling. What a president says matters to the entire world.
The occupant of that office must therefore have the intellectual acuity to master a wide range of subjects, make quick decisions based on the best information available and speak honestly but with discretion.
More than anything, this person must be prepared to handle the relentless pressures of the world's toughest office with grace, wisdom and confidence.
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.
Anne-Marie Slaughter: Standing up to a fight
The qualifications that we should be looking for in a president—and I base this on my experience as a leader, a State Department official, and a citizen--are intelligence, grit, courage, empathy, and the ability to listen to what you don't want to hear.
Sheer smarts should never be undervalued; the president must address an extraordinary range of issues and must be able to think for himself or herself as well as to rely on advisers.
Grit is perhaps more essential in Washington than anywhere else in the world: the dogged determination to keep trying in the face of an obdurate bureaucracy or a hostile legislature.
Courage is essential: the ability to wade into a fight when necessary, to face down the media, to make an unpopular decision.
Empathy is undervalued, but if a President cannot walk in the shoes of a citizen, an immigrant, or a human being half way around the world and feel what that person is feeling, s/he cannot lead in the way that people often yearn to be led.
Finally, a good President will insist on having at least a few staff members who are hired precisely for their ability to tell the boss what others will not—to deliver unpleasant truths and be heard. That is the only way out of the sycophantic bubble that Washington so often becomes.
A final note: Regardless what you think the actual qualifications for President should be, and whether you are a Democrat or a Republican, you should be very suspicious of any effort to denigrate any woman as "unqualified for the job." It touches a raw nerve -- at least for Boomer and Gen X women who have been in the workforce for a while.
Reams of research shows that a man who may have have relatively little experience for a job will be hired or promoted on the grounds that he has great potential and can certainly learn on the job, while a woman in the same situation will be told that she needs a year or two more of experience before she is qualified. Let's not let the potential/performance gap infect our politics.
Anne-Marie Slaughter is president and CEO of New America. She was director of policy planning in the U.S. State Department from 2009 to 2011. She is the author of "Unfinished Business: Women Men Work Family."
H.W. Brands: A vision of the American dream
No one is fully qualified to be president. The job is too big for any man or woman. So we are arguing about degrees of qualification. Successful presidents have possessed varying combinations of experience in government (FDR, among others), strong principles that nonetheless allow compromise with those of differing views (Reagan), flexibility to deal with novel challenges (Truman), and the eloquence to convey a contemporary vision of the American dream to the American people (Lincoln, FDR, Reagan).
No successful president has pandered to Americans' fears. The most successful have appealed convincingly to Americans' hopes. They have reminded us that the land of the free must be the home of the brave.
H.W. Brands is professor and Jack S. Blanton Sr. Chair in history at the University of Texas at Austin. He is the author of numerous books about U.S. history, including "Reagan: The Life" and "Andrew Jackson: His Life and Times."
Donna Brazile: Eyes on the horizon
The most important qualification to be president is this: to possess that rare combination of idealism and pragmatism that our best presidents have had—the ability to see all the way to the horizon while still navigating the hazards on the road directly ahead.
Abraham Lincoln brought about Emancipation not only by bringing his single-minded vision of an America without the abomination of slavery, but by leading an incredibly difficult and complex struggle, both military and political--always concentrating on what was doable at the moment while keeping his eyes on the ultimate prize.
Both Democratic candidates arguably have that combination, although their opponents may question Clinton's idealism or Sanders' pragmatism. Of the GOP candidates, even if you give Ted Cruz credit for his own strain of idealism, he is the least pragmatic member of Congress. And Donald Trump fails miserably on both scores.
Donna Brazile, a CNN contributor and a Democratic strategist, is vice chairwoman for civic engagement and voter participation at the Democratic National Committee. She was campaign manager for Al Gore's presidential campaign in 2000. A nationally syndicated columnist, she is an adjunct professor at Georgetown University and author of "Cooking with Grease: Stirring the Pots in America."
Hugh Hewitt: A nose for the right talent
The greatest modern presidents -- or at least those with the greatest achievements, such as Richard Nixon's opening to the People's Republic of China -- surround themselves with brilliant, sometimes difficult people.
President Reagan had James Baker, Ed Meese, William French Smith, Fred Fielding --and the great George Schultz, Secretary of Everything and a Marine. Nixon of course welcomed both Nelson Rockefeller's "old school," balance-of-power, interventionist Henry Kissinger and liberal Daniel Patrick Moynihan into his circle. The ability to attract and deploy talent in the service of the nation without being threatened or overwhelmed by it is the mark of qualification.
These is room of course for loyalists (but not only loyalists) and for youth (Reagan employed a young John Roberts). But to reach out and empower the best -- as George W. Bush did with Gens. James Mattis, Stanley McCrystal and David Petraeus -- is the necessary ingredient of qualification.
Hugh Hewitt is a lawyer, law professor, author and host of a nationally syndicated radio show. He served in the Reagan administration in posts including assistant counsel in the White House and special assistant to two attorneys general.
Paul Begala: Seeing world through others' experience
I believe empathy is the most important quality a president can have. This is an impossibly large, unimaginably diverse country. The ability to empathize with people of every race, religion, sexual orientation, region, generation, and ideology is critical. A president must be able to put herself -- or himself -- in the Guccis of foreign leaders, the cowboy boots of congressmen, the orthopedic shoes of the elderly, and the flip-flops of the young. Obviously brains help and rhetorical skills are a great asset, but for my money, empathy matters most.
Paul Begala, a Democratic strategist and CNN political commentator, was a political consultant for Bill Clinton's presidential campaign in 1992 and was counselor to Clinton in the White House. He is a consultant to the pro-Hillary Clinton super-PAC Priorities USA Action.
Aaron David Miller: A handle on history
All presidents, political writer Jonathan Alter has said, are blind dates; And since there's no school for presidents, it's very hard to know--regardless of what's on the résumé--just what kind of president we're getting. The self-educated Abraham Lincoln had no real résumé -- a couple of terms in the Illinois House and one in the U.S. Congress; and he was among our greatest presidents, along with Washington and FDR; James Buchanan had one of the best résumés in the presidential biz and turned out to be one of our worst presidents.
So what are the qualities you need to be president? Having worked for a half-dozen secretaries of state of both parties and been around a couple of presidents, I'd suggest two or three. First, an even temperament, or what we might fashionably call emotional intelligence: Understanding yourself and keeping your demons under control so that power, pettiness and narcissistic impulses don't guide you. Richard Nixon and Lyndon Johnson -- and the latter might actually have been a great president had it not been for Vietnam -- couldn't.
Second, the ability to process information: Do you know what you don't know and are you in a hurry to find it out? Whether a president asks the right questions, particularly when weighing whether America will use force abroad, is critical. Should we do it? Can we do it? And what is it likely to cost?
And finally, a knowledge of history, because the past teaches humility and prudence and tempers a president's temptation to give in to the transgressions of omnipotence (I can do everything) and omniscience (I know everything).
Aaron David Miller is a vice president and distinguished scholar at the Woodrow Wilson International Center for Scholars and author of "The End of Greatness: Why America Can't Have (and Doesn't Want) Another Great President
." Miller was a Middle East negotiator in Democratic and Republican administrations. Follow him on Twitter @aarondmiller2.
Van Jones: A strong internal compass
The number one quality that a president needs is a "true north" in terms of values and priorities. In the White House, more consequential things happen in one hour than happen during a whole month in a normal workplace. The pace of incoming data, intel and requests for action is relentless. Surprises are the norm, so plans necessarily change on the fly.
Meanwhile, opponents (abroad, in the media and in other branches of government) work round the clock to undermine your efforts. Without a "true north," drift and fragmentation lead to blunders, wasted effort and missed opportunities. But with it, despite everything, the most important goals can be achieved. A president must have, above all else, a strong internal compass and a clear sense of what really matters to him or her, in the long run.
Van Jones is president of Dream Corps and Rebuild the Dream, which promote innovative solutions for America's economy. He was President Barack Obama's green jobs adviser in 2009. A best-selling author, he is also founder of Green for All, a national organization working to build a green economy. Follow him on Twitter @VanJones68.
David Boaz: A firm grasp of reality
I grew up during the Lyndon Johnson and Richard Nixon years, when unwise and unconstitutional actions drove two presidents from office.
The most important qualifications for a president are: first, good character, including a realization that a president is not a king; second, a recognition and acceptance of the Constitution's limitations on the power of the president, the executive branch, and the federal government; and third, a firm grasp of reality, from the laws of economics to the difficulties of waging war in Asia, the Middle East, or elsewhere.
Those seem like minimal standards, but they're apparently hard to find in people who seek the presidency.
David Boaz is executive vice president of the Cato Institute and author of "The Libertarian Mind"