WASHINGTON — Donald Trump said during his campaign that U.S. presidents had made "stupid" foreign deals, alleging that they gave too much away to allies and adversaries alike, and insisted "the world is laughing at America's politicians."
National security and foreign policy experts called him naive and reckless, and warned that sensitive global diplomacy is nothing like the bare-knuckled world of New York real estate or the raw voyeurism of reality TV.
Now, as he prepares to meet North Korean leader Kim Jong Un in a summit in Singapore, Trump is putting his much-touted negotiating skills and his iconoclastic worldview to the ultimate test.
"There's no way to exaggerate how important the summit is for President Trump," said Douglas Brinkley, a presidential historian.
If Trump succeeds, "suddenly he could say, 'There's a method to my madness, that it is about the art of the deal, and I am a big-time negotiator,'" Brinkley said.
But if it fails, Tuesday's summit becomes a capstone to Trump's mounting domestic problems, including the Russia investigation and his stalled legislative agenda.
"His whole presidency is in danger," Brinkley said.
To Trump, the summit itself has been the big prize, even though his predecessors avoided meeting North Korea's leaders for fear of giving a photo op to an outlaw dynasty.
"Ultimately he's going to decide what is good enough for denuclearization regardless of the history or anything else," said Victor Cha, who headed Asian affairs in the National Security Council under President George W. Bush and took part in nuclear talks with North Korea at the time.
Cha worries that Trump, who has shunned diplomacy in other parts of the world, is choosing to make his maiden attempt at a peace deal in North Korea.
"He has picked the hardest issue to do this, with the highest stakes, when everybody else has failed before him," said Cha, whom Trump briefly considered appointing as U.S. ambassador to South Korea. "And it's not like everybody else is stupid."
Trump has rejected experts at every step in his march to the summit. He posted on Twitter cartoonish taunts of Kim last year, threatened to unleash "fire and fury ... like the world has never seen," and then impulsively reversed course by accepting Kim's invitation to meet, with little or no consultation from aides.
He has rejected lengthy briefings arms control, and alarmed allies in Tokyo and Seoul by saying he planned to wing it after he sizes up Kim in person. He also surprised diplomats by saying he would stop calling for "maximum pressure" on Pyongyang, and suggesting more summits with Kim, although the White House denied those were concessions.
Trump said Saturday as he left a Group of 7 meeting in Canada and prepared to board Air Force One for Singapore that he would know "within the first minute" of meeting Kim whether they could reach a deal.
"Just my touch, my feel. That's what I do," he said. "It's unknown territory in the truest sense, but I really feel confident."
Kim "wants to do something great for his people ... and he won't have that opportunity again, Trump said. It's a one-time shot, and I think it's going to work out very well."
In Trump's rush to meet Kim, he has forced his own national security team to upend the usual planning for a presidential summit. Normally, diplomats and subject experts patiently negotiate agreements before allowing the leaders to meet in carefully scripted settings.
The summit typically comes last, in part because meeting a U.S. president is viewed as an incentive and a reward, a chance to be seen as equals on the global stage.
For Trump, the question is whether he can gain enough from Kim to declare a major foreign policy achievement, one that eluded the presidents he so often disdains. He has vacillated in recent weeks, initially demanding swift nuclear disarmament, and then last Friday telling a North Korean envoy, "Take your time."
Trump has sought to lower the bar for success. He no longer talks about winning a Nobel Peace Prize or throwing a celebration when the talks conclude. He instead described his Singapore meeting with Kim as a "getting-to-know-you meeting, plus."
Even some of Trump's doubters carry shards of hope, and a bit of wonderment, that his unconventional diplomacy may crack the North Korean enigma and produce a meaningful deal to cut if not eliminate the nuclear threat.
"Donald Trump doesn't have to be a genius. He just has to say 'yes' at the proper time," said Robert L. Gallucci, a former ambassador at large who led nuclear talks with North Korea in 1994 for the Clinton administration.
Some experts credit Trump's idiosyncratic Twitter posts and bluster with keeping the summit alive, despite a few somersaults along the way, even as they worry that he has given up considerable leverage in the process _ and that North Korea can't be trusted to keep its promises in any case.
Catherine Killough, who focuses on North Korea's nuclear and missile development at the Ploughshares Fund, a global security foundation in Washington, said she believes "the stars have aligned on the Korean peninsula."
Kim does not behave like his father or grandfather, who ruled the country before him and were driven to develop nuclear weapons with singular focus, she said. Now that he has achieved that goal, Kim has made clear he wants to improve North Korea's fragile economy, which could get a huge boost if he strikes a deal with Trump.
"I have a very cynical view of President Trump, but I think at the same time this could work," Killough said. "We don't get very far by repeating the same old tactics."
Kim has promised to stop nuclear and ballistic missile tests, and his government said it destroyed a major nuclear test site inside a mountain. It also released three Americans it had imprisoned, two of them arrested since Trump took office.
But most Korea experts believe that Kim is gaining far more than he has given up so far.
In addition to no longer demanding swift disarmament, Trump has relaxed some of the economic and diplomatic pressure Kim faces from global powers. Trade has measurably increased as China and Russia ease on enforcing sanctions.
Moreover, the leader of one of the world's most isolated and repressive nations is suddenly in demand on the international circuit. He made his first two foreign trips as ruler, visiting China twice since March to meet with and stroll on a beach with President Xi Jinping.
Russia's foreign minister, Sergei Lavrov, flew to Pyongyang to meet Kim for the first time. So did Secretary of State Mike Pompeo _ twice, though first as CIA director.
Trump also has disavowed comments from his hawkish national security adviser, John Bolton, after Pyongyang complained about them and threatened to cancel the summit. Bolton was nowhere to be seen when Trump welcomed a North Korean official to the Oval Office last Friday, and later escorted him to his car past TV cameras.
Trump often acts on impulse. But he is guided by long-term instincts, including a desire to surprise people, prove the experts wrong and do things others failed to do.
His boldest foreign policy decisions have all fit those parameters: withdrawing from the Paris climate agreement, pulling out of the Iran nuclear deal, imposing steel and aluminum tariffs on Mexico, Canada and the European Union, and moving the U.S. Embassy in Israel from Tel Aviv to Jerusalem. Each, for differing reasons, has enraged allies.
But the biographers who have studied Trump's career since he was an apprentice in his father's real estate company say Trump relies far more on his salesmanship than actual deal-making prowess.
They see the Kim summit as unlikely to focus on the details of denuclearization but rather as a political play designed for a domestic base that likes to see a president in perpetual motion.
They predict that Trump will take what he can from Kim _ be it a photo op, a disarmament deal or something in between _ so long as he can sell it as a big win back home.
In his business career, "he was all about ballyhoo and demands," said Michael D'Antonio, the author of "Never Enough," a Trump biography. "But when it came down to the actual deal, he never did better than anyone else."
(Tracy Wilkinson and David Lauter contributed to this report.)