The tweets underscore a key irony of the Trump era: Some of the president’s fiercest critics during the 2016 race have since transformed into his most passionate defenders, including Secretary of State Mike Pompeo, who warned that Trump would be an “authoritarian president”; GOP Senator Lindsey Graham, who denounced Trump as “a race-baiting, xenophobic, religious bigot” who would destroy the Republican Party; and acting chief of staff Mick Mulvaney, who called Trump a “terrible human being” right before the 2016 election.

Grenell seems to have undergone a similar evolution.

“Trump is dangerous. Wake up. He’s reckless,” he replied on another occasion to a user who had written “vote Trump.” He urged his followers to read Trump’s interview with The Washington Post editorial board, in which Trump said, “I think NATO as a concept is good, but it is not as good as it was when it first evolved … I’m not even knocking it, I’m just saying I don’t think it’s fair, we’re not treated fair.”

“NATO needs reforming. But Trump is questioning its usefulness,” read another deleted Grenell tweet from March 24, 2016.

Five days later, in another since-deleted tweet, Grenell wrote, “If you think Trump knows foreign policy issues then absolutely yes, you are stupid.” Vox highlighted some of Grenell’s criticisms in March 2017, when Trump was considering nominating Grenell to be U.S. ambassador to NATO. POLITICO and Nisos were able to recover more than 1,000 deleted tweets belonging to Grenell’s account via analysis of open source information through a proprietary capability that extracted and screen-captured archived tweets via the Wayback Machine.

Grenell did not respond to a request for comment, nor did he dispute the authenticity of the tweets, but a person close to him said: “As a foreign policy commentator, he opined on foreign policy issues and ideas. He strongly supported Donald Trump as the best GOP candidate overall.”

Grenell’s appointment as acting DNI comes as Trump, in a post-acquittal victory lap, has begun purging his administration of anti-Trump career employees and political appointees. But the fairly conventional Republican view of U.S. foreign policy Grenell articulated in 2016 appears to be at odds with Trump’s complete dismissal of international organizations, treaties and alliances.

“NATO only works when the US leads it,” reads another deleted Grenell tweet from March 24, 2016. “The UN, too.” Trump has berated the United Nations as “a waste of time and money,” and “just a club for people to get together, talk and have a good time.”

But Grenell also appeared to prefer Trump’s rivals for the 2016 GOP presidential nomination, Kasich and Carly Fiorina. Even former Florida Gov. and GOP candidate Jeb Bush got some love: “@JebBush is right,” Grenell’s account tweeted on Oct. 28, 2015, during that campaign cycle’s third GOP debate. “@DonaldTrump talks about foreign policy like it’s a simple board game. #Unserious.”

During a GOP debate on Jan. 28, 2016, Grenell’s account heaped praise on Fiorina, the former Hewlett-Packard CEO. “The GOP needs #CarlyFiorina,” reads one tweet from that night “[email protected] for the win. #Loveher,” reads another.

By February, Grenell appears to have moved over to the Kasich camp. “John Kasich is presenting the most new ideas,” reads one tweet from Feb. 13, 2016, the night of another GOP debate.

During the March 10, 2016 debate, Grenell’s account tweeted: “John Kasich is very good and comfortable on foreign policy.” During a March 22, 2016, Kasich, appearance on the Fox Business show “Varney & Co,” Grenell’s account tweeted: “@JohnKasich is on with @Varneyco talking the most intelligently about Brussels attacks. He is strong and yet thoughtful.”

On March 24, 2016, when a new Pennsylvania poll was released, Grenell’s account wrote: “Pennsylvania can save America by voting John Kasich,” adding in another tweet: “John Kasich needs to stay in this race until the end. Many people know [Ted] Cruz just can’t win in November.”

A former Kasich strategist, John Weaver, told POLITICO that Grenell was never involved with the campaign in any capacity. Though “he did show good judgment for a bit,” Weaver joked.

Grenell has long espoused hawkish views toward Russia. He was harshly critical of what he viewed as Obama's solicitude toward Moscow: In 2014, for instance, he called for a larger missile defense shield in eastern Europe after Russia’s disputed annexation of Crimea and a surge in funding for the U.S. government-funded outlet Radio Free Europe/Radio Liberty.

“NYT says Putin defies ‘the United States,’” Grenell wrote in March 2014. “Why isn’t it Putin defies Obama?”

There's no indication that Grenell, whom Trump nominated to be U.S. ambassador to Germany in September 2017, has dialed back his criticism of Russia's policies.

But he does appear to have atoned for his anti-Trump commentary. He began supporting Trump publicly after he became the GOP nominee, writing in June 2016 that he would support the Republican candidate over Hillary Clinton and, in August, that the election “is a choice between 5,000 conservative appointees and 5,000 liberal appointees.”

He also began to mock reports that said Russia had interfered in the election to boost Trump’s candidacy, writing in December 2016: “[T]hose Russians must have demanded that Hillary not campaign in Wisconsin and Michigan, too.” And he promoted the WikiLeaks disclosures, praising news organizations that reported extensively on the hacked DNC materials and criticizing those that didn’t.

“The WikiLeaks reporting is excellent,” he tweeted at conservative news outlets Daily Caller and Independent Journal Review on Oct. 12, 2016, days after WikiLeaks released emails Russia had stolen from Hillary Clinton’s campaign chairman John Podesta. “Keep it up,” he wrote. On Oct. 14, 2016, Grenell complained that the Twitter feed of MSNBC’s Katy Tur had “almost no WikiLeaks content,” and called on NBC News executives to “take action against her advocacy.”

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By that point, the Obama administration had released an unprecedented joint statement from intelligence officials—minutes before the Podesta emails WikiLeaks dump—accusing the Russian government of interfering in the election through hacking.

But Grenell was undeterred. In January 2017, his account tweeted “this sums it up” above a meme of two dogs saying: “We’re glad you’re home! The Russians pooped in the hallway,” implying that Democrats were using Russia as a scapegoat for their loss. Trump has repeatedly cast doubt on the intelligence community’s assessment that Russia interfered in the 2016 election to boost his candidacy.

As acting director of National Intelligence, Grenell will oversee the very intelligence agencies that drew the conclusions about Russia’s interference that Grenell downplayed. “Russia always tries to interfere in elections,” Grenell wrote on April 3, 2017, in a since-deleted tweet. “Obama should have done something about the fact they hacked the DNC. He was President.”

At ODNI, Grenell will also have declassification authority, and has aligned himself with Trump’s claims that the Obama administration was “spying” on his campaign. In one deleted tweet from April 2017, Grenell wrote: “Obama team listened in on Trump team, then selectively leaked info. Most people call this spying.”

One of Grenell’s senior advisers at ODNI, Kash Patel, played a key role as a Hill staffer in helping Republicans, particularly former House Intelligence chairman Rep. Devin Nunes (R-Calif.), try to discredit the Russia probe in the year after Trump’s victory.

“@DevinNunes is solid,” Grenell wrote on March 24, 2017 in another since-deleted tweet. Nunes had briefed reporters that day on his findings about potential surveillance of the Trump campaign. “Measured, focused, and serious,” Grenell added of Nunes.

Nunes stepped aside from the House Intelligence Committee’s Russia probe two weeks later as he came under investigation by the House Ethics Committee over reports he “may have made unauthorized disclosures of classified information.” He was ultimately cleared of wrongdoing.

Daniel Lippman contributed to this report.