WASHINGTON: President Barack Obama had some simple advice for Hillary Rodham Clinton in the days before the launch of her presidential campaign. “If she’s her wonderful self, I’m sure she’s going to do great,” he said.

That sounds easy enough.

But plenty of politicians — Clinton among them — have found it a tricky proposition to just be themselves in the maelstrom that is a presidential campaign.

Clinton spent a good share of her 2008 primary campaign trying to find the right formula for revealing her true self, projecting first strength, then empathy. Four years later, a buttoned-up Republican Mitt Romney, described by friends as warm and generous, never shook the stereotype of callous rich guy. In 2000, Democrat Al Gore, cast as a stiff, struggled to connect with voters in a more natural way.

Sure, policy is important, but when running for president, finding an authentic way to mesh it with one’s personality matters, too.

What can be so hard about being yourself?

“It’s not just tricky for candidates, it’s tricky for most people,” says Dan Schnur, who worked on four Republican presidential campaigns.

“A campaign is like the world’s longest job interview, and even though most of us like to think that we’re being our natural selves when we interview for a new job, it’s only human nature to self-edit ourselves and try to make the best possible impression,” says Schnur, director of the University of Southern California’s political institute.

Yet the urge to impress can make candidates so risk-averse that they become timid and lose the spontaneity and authenticity that voters crave. In Clinton’s case, she suffers from the added burden of constantly being measured against her husband, former President Bill Clinton, an extraordinary natural political talent.

“It’s not that she isn’t a good politician,” says Schnur. “She’s just not as good as he is.”

Republicans in the 2016 field face their own challenges in calibrating how to be both appealing candidates and true to themselves.

Kentucky Sen. Rand Paul, who got testy with reporters within hours of launching his presidential campaign this past week, gets praise from some for his direct style but allowed that he’s got to learn how to contain his temper and hold his tongue.

“It’s hard to have a true interaction sometimes,” Paul said of campaigning.

New Jersey Gov. Chris Christie, a potential GOP candidate who is famous for his blow-ups, says he’s trying to do better, but he’ll never be plain “vanilla.”

“I think we’ve had too much of people in public life pretending to be something,” he said. The challenge for candidates is to find a way to sync their personalities, whatever they may be, with their political pitch in a complementary way.

And they have to do it in a confessional culture that demands familiarity and intimacy from public figures like never before.