The day after President Donald Trump returned to office, Sam Altman, the CEO of tech giant OpenAI, stood behind the presidential seal at the White House and praised the newly sworn-in president for the $500 billion “Stargate” initiative he was joining to build an artificial intelligence infrastructure in the United States.

Altman said it wouldn’t have been possible without Trump.

“For AGI [artificial general intelligence] to get built here, to create hundreds of thousands of jobs, to create a new industry centered here, we wouldn’t be able to do this without you, Mr. President, and I’m thrilled that we get to,” Altman said as he and other industry leaders smiled for photos in the Roosevelt Room.

The chummy announcement represented a stark reversal for Altman, who — in the early days of Trump’s first term — emerged as one of Silicon Valley’s first and most vocal critics of the president.

From 2016 through 2022, Altman repeatedly warned about what he saw as the dangers posed by Trump’s leadership and his policies. During the 2016 campaign, he compared Trump to Hitler in 1930s Germany, and he called on other tech companies to stand against Trump in the early days of the new administration. He donated hundreds of thousands to Democratic causes and candidates, including $200,000 to help reelect President Joe Biden in 2024.

After Trump announced the “Stargate” deal, the OpenAI CEO appeared to address his reversal in a post on X, writing that “watching [Trump] more carefully recently has really changed my perspective on him,” and adding, “I’m not going to agree with him on everything, but I think he will be incredible for the country in many ways!”

Other tech leaders have shifted their stance on Trump in recent years, even more so since his 2024 election win.

Earlier this month, Mark Zuckerberg’s Meta announced the end of its fact-checking program and eased restrictions on discussions about topics such as immigration and gender identity, following longstanding criticism from President Trump and his allies.

‘An unprecedented threat’

Altman’s public opposition to Trump began during the 2016 presidential campaign when, in October of that year, Altman made his first-ever presidential endorsement by backing Hillary Clinton.

“I am endorsing Hillary Clinton for president. I’ve never endorsed a presidential candidate before, but I’m making an exception this year, because this election is exceptional,” Altman wrote in a blog post on Oct. 16, 2016, titled “The 2016 Election.”

“Donald Trump represents an unprecedented threat to America, and voting for Hillary is the best way to defend our country against it,” Altman wrote.

Months earlier, in the heat of the presidential campaign, Altman had published a scathing critique of Trump, writing, “He is irresponsible in the way dictators are.”

“To anyone familiar with the history of Germany in the 1930s, it’s chilling to watch Trump in action,” Altman wrote in June 2016. “Though I know intellectually it’s easy in hard economic times to rile people up with a hatred of outsiders, it’s still surprising to watch this happen right in front of us.”

“Hitler taught us about the Big Lie — the lie so big, and so often repeated, that people end up believing it,” Altman wrote. “Trump’s Big Lie is hiding in plain sight. His Big Lie is that he’s going to Make America Great by keeping us safe from outsiders.”

After Trump’s victory, Altman called on his fellow tech leaders to “take a stand” against the new Trump administration in the wake of Trump’s executive order known as the so-called Muslim ban, which Trump called “a total and complete shutdown of Muslims entering the United States.”

Altman called the 2017 order “a breach of America’s contract with all the immigrants in the nation.” The order spurred nationwide protests and legal challenges before being modified and then overturned by President Biden in 2021.

He urged the tech industry to take action, writing on his personal blog, “The tech community is powerful. Large tech companies in particular have enormous power and are held in high regard. We need to hear from the CEOs clearly and unequivocally.”

He added that employees at tech companies “should push their companies to figure out what actions they can take.”

“It would be particularly embarrassing for us to fall for this — we are a nation of immigrants, and we know that immigrants built this country (and Trump, of course, is the grandson of immigrants and married to an immigrant),” Altman wrote.

Altman himself took action by launching a website called “Track Trump,” which monitored Trump’s fulfillment of his 2016 campaign promises over his first 100 days in office. He shared the website in a February 2017 tweet in which he said, “For all the noise, Trump hasn’t actually done very much yet.”

‘I think Trump is terrible’

Altman’s public criticism continued throughout Trump’s first presidency. In a March 2017 tweet, Altman posted, “I think Trump is terrible and few things would make me happier than him not being president.”

“If you elect a reality TV star as President, you can’t be surprised when you get a reality TV show,” Altman wrote in July 2017.

At a “Talks with Google” event in October 2017, Altman defended his outspoken criticism of Trump. Acknowledging that “if you “piss off the president, he might do bad things to you,” Altman nevertheless said that “when the future of the republic is at risk, the duty to the country and our values transcends the duty to your particular company and your stock price.”

“I think I started that a little bit earlier than other people, but at this point I am in really good company,” Altman added.

Later, in the wake of Trump’s 2020 election loss, Altman praised LinkedIn chairman and Democratic supporter Reid Hoffman, writing on Twitter, “Very few people realize just how much @reidhoffman did and spent to stop Trump from getting re-elected — it seems reasonably likely to me that Trump would still be in office without his efforts. Thank you, Reid!”

Democratic donations

In recent years, Altman has himself contributed hundreds of thousands of dollars to Democratic candidates and causes, including giving $200,000 in 2023 to the Biden Victory Fund, the joint fundraising committee that sought to reelect Joe Biden in 2024, according to federal election commission records reviewed by ABC News.

Early in the 2020 election cycle, he contributed to a slew of Democratic primary presidential contenders, including to Sen. Elizabeth Warren, then-Sen. Kamala Harris and Andrew Yang, then later gave $100,000 to the Biden Victory Fund in the final weeks of the 2020 campaign.

He also gave $100,000 each to the pro-Democratic super PACs American Bridge PAC and Senate Majority PAC.

He wasn’t an active political contributor during the 2016 election cycle, but gave a total of $1,500 to the Obama campaign in 2008 and 2012.

Although Altman has almost exclusively donated to Democrats, he has also donated to a handful of Republicans, including California Reps. Darrell Issa and Jay Obernolte, Rep. John Curtis of Utah, and Sen. Marsha Blackburn of Tennessee.

Then, after Trump was reelected this past November, Altman was among the first corporate executives to publicly announce their donation to the Trump-Vance Inaugural Committee, as tech companies including Meta and Amazon lined up to financially support Trump’s inauguration.

An OpenAI spokesperson confirmed to ABC News that Altman donated $1 million to the inaugural committee in December.

Last Monday, Altman was among the select number of tech executives spotted attending Trump’s swearing-in ceremony inside the Capitol rotunda.

“President Trump will lead our country into the age of AI, and I am eager to support his efforts to ensure America stays ahead,” Altman wrote in a statement to ABC News at the time about his inauguration contribution.