Republican presidential nominee Donald Trump listens to Democratic presidential nominee Hillary Clinton during the presidential debate at Hofstra University in Hempstead, N.Y., on Sept. 26. (Patrick Semansky/AP)

Fully repeal the “disaster” Affordable Care Act? After meeting with President Obama, Donald Trump said maybe he’ll keep some of it.

Revive waterboarding of terrorism suspects? Eh, maybe the promise of cigarettes and beer will work even better, the president-elect said after talking with a retired general.

Treat climate change like a “hoax”? Well, maybe humans are doing some things wrong, Trump conceded after a New York Times columnist laid out a case.

Since winning the election, Trump has made clear that even his firmest positions are open to change and that he can be easily persuaded by the well-known figures now clamoring to give him advice.

President-elect Trump made some serious promises during the 2016 campaign – but appears to have changed his mind on several of them in the weeks since. (Peter Stevenson/The Washington Post)

The president-elect tends to echo the last person he spoke with — or the last thing he saw on TV — making direct access to him all the more valuable, especially as he selects members of his administration. Just this week, Trump said he decided to intervene to keep open an Indiana furnace factory after watching a network news report.

That open-minded nimbleness may have helped Trump win the election and charm voters who are bored with politicians so set in their ways that they can’t readjust to changing moods. But it also poses clear risks as Trump prepares to govern and will be forced to commit to positions.

“No one should have ever mistaken Trump for a man of any fixed principles or of having any sort of intellectual framework beyond his self aggrandizement and bluster,” said Rick Wilson, a Republican strategist and longtime Trump critic. “His followers thought he meant every word he said. But it’s obvious that Trump has little if any actual ideological consistency despite his promises.”

He added: “Imagine when it’s major, international crisis business, not this pre-game warm-up.”

Unlike presidents before him, Trump has often rejected the help of traditional policy advisers and briefers, claiming to already know what he needs to know. Instead, Trump watches endless cable television, consults with his adult children and chats up a line of guests to Trump Tower in New York and his private club in Palm Beach, Fla. He also regularly takes the calls of fellow wealthy businessmen with their own ideas to share.

Sometimes an uttered idea or a turn-of-phrase sticks — especially when offered by someone with some celebrity status who is careful to praise and not criticize the president-elect.

Obama was one of Trump’s sharpest critics on the campaign trail, but since Election Day, the president seems to have gone out of his way to refrain from publicly insulting his replacement, despite numerous opportunities to do so.

Obama’s signature Affordable Care Act was one of the topics covered when the two men met at the White House. For more than a year, Trump has promised to fully repeal and replace it with something much better — a vague pledge that he stuck with even when confronted with the reality that major reform doesn’t happen quickly.

Soon after that meeting, Trump told the Wall Street Journal that he might be open to keeping parts of the legislation, perhaps amending it instead of fully repealing it.

Since then, Trump has also repeatedly met with 2012 Republican nominee Mitt Romney, whom he once described as “sad and pathetic,” a “loser” and a “choker” who should have won the election and “walks like a penguin.” But now that Romney is publicly praising Trump for doing what he was unable to do, Trump is seriously considering him for secretary of state.

When Trump met with editors and reporters at the New York Times after the election, columnist Thomas Friedman asked Trump about climate change — while also praising Trump’s seaside golf courses and mentioning his own recent television appearance. As Friedman and others pressed Trump on the issue, the president-elect admitted that “there is some connectivity” between human activity and climate change, although he doesn’t want to put companies at a disadvantage to fight it.

“I’m going to be studying that very hard, and I think I have a very big voice in it,” Trump said. “And I think my voice is listened to, especially by people that don’t believe in it.”

Members of Trump’s campaign staff have long tried to master the tricky art of getting him to do and say what they wanted without him realizing it. On the campaign trail, the easiest way to gain influence was to constantly travel with Trump on his plane, allowing them to monitor his conversations, watch him react to cable news and casually mention ideas of their own.

Trump’s third and final campaign manager, Kellyanne Conway, has repeatedly compared working with Trump to tricking her young children into doing what she wants. Conway has said that she’s careful to not tell Trump what to do and instead gives him a few options to pick between, delivered in snappy soundbites.

During an interview this summer with The Washington Post, Conway illustrated this point by telling a story about her 11-year-old daughter who wanted to wear a turquoise shirt on Memorial Day, instead of a blue shirt as her mother wanted. Conway laid out four blue options for her daughter to freely choose between and “minutes later, she came out in one of those shades.”

When Conway took over the campaign in August, along with new campaign chief executive Stephen Bannon, the new leadership tried to move the center of power from Trump’s plane back to Trump Tower. But as Election Day approached, Bannon and other top aides were nearly always on the plane with Trump.

Praise is often the key to influencing Trump, who has made clear that he does not like to be questioned or challenged.

Nearly a year ago, staffers at the now-defunct gossip website Gawker decided to “set a trap for Trump” on Twitter, tricking him into retweeting a quote from Italian fascist dictator Benito Mussolini. They created a “bot” that regularly fired tweets at Trump containing a dictator quote and a dose of flattery. In February, Trump took the bait and hit retweet.

“We came up with the idea for that Mussolini bot under the assumption that Trump would retweet just about anything, no matter how dubious or vile the source, as long as it sounded like praise for himself,” Gawker reported at the time.

Yet there is unpredictability to Trump. He has been known to stubbornly cling to positions that are problematic for legal, constitutional or logistical reasons, rejecting waves of advice on how to better tailor his message or approach. But then, seemingly with just one conversation, he can suddenly change.

Take the example of waterboarding.

Ahead of the Republican primaries, Trump declared that “torture works” and promised to bring back waterboarding. Even if these methods don’t produce usable information, Trump said at one point, terrorism suspects “deserve it anyway.”

“I love it, I love it, I think it’s great,” Trump said at a rally in Indianapolis in April.

Although this earned Trump applause at rallies, few counterterrorism experts or elected lawmakers agreed with him. Cable television, news websites and Twitter filled with explanations for why Trump cannot and should not do this.

“[T]hese forms of torture not only failed their purpose to secure actionable intelligence to prevent further attacks on the U.S. and our allies, but compromised our values, stained our national honor, and did little practical good,” Sen. John McCain (R-Ariz.) said in February, one of many passionate pleas.

For a year, Trump refused to budge on the issue. He did concede that he wouldn’t force members of the military to break the law, and so he would change the statutes before requiring them to resume waterboarding.

Then came Trump’s post-election meeting with retired Marine Gen. James “Mad Dog” Mattis, a four-star general who is being considered for secretary of defense.

“So, I met with General Mattis, who is a very respected guy,” Trump said during the New York Times meeting. “In fact, I met with a number of other generals, they say he’s the finest there is. . . . General Mattis is a strong, highly dignified man.”

Trump said he asked Mattis for his thoughts on waterboarding.

“I was surprised,” Trump said. “He said: ‘I’ve never found it to be useful.’ He said: ‘I’ve always found, give me a pack of cigarettes and a couple of beers and I do better with that than I do with torture.’ And I was very impressed by that answer. I was surprised, because he’s known as being like the toughest guy.”

Trump said he had not yet changed his mind on waterboarding — and that if the American people really want it, he will do it. But he repeatedly said he was “impressed” with Mattis’s answer.

“You know, he’s known as ‘Mad Dog Mattis,’ right?” Trump said. “Mad Dog for a reason. I thought he’d say, ‘It’s phenomenal, don’t lose it.’”