President Barack Obama weighed in on the state of the 2016 presidential campaign, refraining from making an endorsement in the Democratic primary but offering warm praise of Hillary Clinton.

“The fact that she’s extraordinarily experienced – and, you know, wicked smart and knows every policy inside and out – sometimes could make her more cautious and her campaign more prose than poetry, but those are also her strengths,” Obama told Politico’s Glenn Thrush.

Obama avoided criticizing Clinton’s chief rival, Sen. Bernie Sanders – the sitting president has traditionally remained neutral in his party’s race for a successor, and the White House has said Obama would do the same – but he flatly rejected suggestions that Sanders’ insurgent campaign is analogous to his own historic 2008 run.

Sanders had clearly tapped into “a running thread in Democratic politics” that is frustrated with politicians’ hesitance to unabashedly embrace progressive ideals, Obama said. At the same time, he added, he was once “some untested kid” whom the voters and the press had to “run this guy through the paces a little bit.”

Sanders, he added, has yet to undergo that kind of close examination.

“If Bernie won Iowa or won New Hampshire, then you guys are going to do your jobs and, you know, you're going to dig into his proposals and how much they cost and what does it mean, and, you know, how does his tax policy work and he's subjected, then, to a rigor that hasn't happened yet, but that Hillary is very well familiar with,” Obama said.

The president reflected on his hard-fought, at times bitter campaign against Clinton in 2007 and 2008, but said her service as his secretary of state would flatten the learning curve if she becomes president.

“It means that she can govern and she can start here, [on] day one, more experienced than any non-vice president has ever been who aspires to this office,” he said. “Her strengths, in terms of the ability to debate, the ability to, I think, project genuine concern in smaller groups and to interact with people, where folks realize she’s really warm and funny and engaging.”

In his piece accompanying the interview, Thrush described Obama as “laboring mightily to remain neutral during Hillary Clinton’s battle with Bernie Sanders in Iowa,” adding that the president “couldn’t hide his obvious affection for Clinton or his implicit feeling that she, not Sanders, best understands the unpalatably pragmatic demands of a presidency he likens to the world’s most challenging walk-and-chew-gum exercise.”

Obama was effusive in his praise of Clinton as a candidate and as his one-time political adversary.

“We had as competitive and lengthy and expensive and tough primary fight as there has been in modern American politics, and she had to do everything that I had to do, except, like Ginger Rogers, backwards in heels,” Obama said.

“She had to wake up earlier than I did because she had to get her hair done. She had to, you know, handle all the expectations that were placed on her,” the president said. “She had a tougher job throughout that primary than I did and, you know, she was right there the entire time and, had things gone a little bit different in some states or if the sequence of primaries and caucuses been a little different, she could have easily won.”

Clinton remains a substantial front-runner in national polls, but trails Sanders in New Hampshire and is neck-and-neck with the Vermont senator in Iowa, where voters head to the caucuses in just more than a week.

Her disadvantage, Obama said, is not that she is any less progressive, but her lengthy career in the public eye has made her more familiar to voters, compared to the “bright, shiny object” that is Sanders, an unorthodox, self-described Democratic Socialist from a small, mostly rural state.

“Bernie came in with the luxury of being a complete longshot and just letting loose,” Obama said. “I think Hillary came in with the – both privilege and burden of being perceived as the frontrunner. And, as a consequence, you know, where they stood at the beginning probably helps to explain why the language sometimes is different.”

“What Hillary presents is a recognition that translating values into governance and delivering the goods is ultimately the job of politics, making a real-life difference to people in their day-to-day lives,” the president said. “I don't want to exaggerate those differences, though, because Hillary is really idealistic and progressive. You'd have to be to be in, you know, the position she's in now, having fought all the battles she's fought and, you know, taken so many, you know, slings and arrows from the other side.”

While Obama won’t formally endorse Sanders or Clinton, he emphasized the importance of beating the Republican nominee in November.

“The relevant contrast is not between Bernie Sanders and Hillary Clinton,” he said. Instead, it’s “between Bernie and Hillary and Donald Trump and Ted Cruz and the vision that they're portraying for the country and where they want to take us and how they think about everything from tax policy to immigration to foreign policy.