For more than 10 hours this week, President Trump and his allies used the unfiltered platform of a national political convention to paint a portrait of two Americas that do not exist.

In one — a misrepresentation of life under Trump — the coronavirus has been conquered by presidential leadership, the economy is at its pre-pandemic levels, troops are returning home, and the president is an empathetic figure who supports immigration and would never stoke the nation’s racial grievances.

In the other — a hypothetical preview of a Joe Biden presidency that mischaracterizes many of his proposals — police are defunded, taxes are increased, infanticide is legal, suburbs are abolished and cities burn as violence spreads nationwide.

“No one will be safe in Biden’s America,” Trump said Thursday in a speech that described the upcoming election as a choice between a dystopian socialist future under Democrats and a resurgent America under Trump.

While all political confabs involve some level of spin and revisionism, the Republican National Convention this year has stood out for its brazen defiance of facts, ethical guidelines and tradition, according to experts on propaganda and misinformation. While Trump, a former reality television star, has long trafficked in mistruths and innuendo, the broad cast of characters who took up his tactics during prime-time speeches underscores how his brand of politicking has taken root in the GOP.

The result was a four-day display of propaganda-style programming, said Peter Pomerantsev, a former Russian-television producer and author of “Nothing Is True and Everything Is Possible,” a memoir that describes the Kremlin’s efforts to manipulate the news.

“It reminds me of things I’ve seen in Russia before,” he said. “Facts don’t really matter in this context. You’re just telling different people what they want to hear, so facts become tertiary. They’re not trying to even win a debate; they’re trying to feed people’s confirmation biases and their fears.”

A carousel of Trump endorsers and family members used taped speeches and the backdrop of federal property to depict a swift descent into radicalism and chaos if Biden is elected in November. They described the former vice president as an avatar for ­socialism who would wreck the economy with trillion-dollar tax increases, corruptly enrich his family members and enact job-killing bans on fracking and fossil fuels.

By contrast, the convention used highly produced videos, emotional testimonials and surprise appearances to portray Trump in a positive light. The portrayals were often at odds with the policies and behaviors Trump has embraced during his turbulent first 3 ½ years in office.

The contrast was perhaps best illustrated by Trump’s decision to host a naturalization ceremony for immigrants at the White House on Tuesday, with videotaped footage that aired as part of the Republican convention’s “Land of Opportunity” programming that evening.

“Today America rejoices as we welcome five absolutely incredible new members into our great American family,” Trump said during the ceremony, the first to be conducted at the White House for apparent political purposes. “You’re now fellow citizens of the greatest nation on the face of God’s earth. Congratulations.”

During his administration, Trump has made prolific use of his executive authority to restrict immigration and make it harder for noncitizens to naturalize. The president has called for restricting family-sponsored migration, deriding the largest category of legal immigrants as beneficiaries of “chain migration.”

Neimat Awadelseid, one of the immigrants who participated in the ceremony, obtained citizenship through her brother after coming to the United States from Sudan. Earlier this year, Trump issued a proclamation that barred citizens of Sudan, along with those of several other African countries, from applying to move to the United States through a diversity visa lottery, citing national security concerns. Awadelseid described Trump’s policy on Sudan as “painful.”

In 2018, Trump referred to African nations as “shithole” countries, questioning why immigrants from that part of the world were allowed to come to the United States.

Leon Rodriguez, who ran the U.S. Citizenship and Immigration Services during the Obama administration, said Trump’s use of a naturalization ceremony to boost his political fortunes was a sign that the president now realizes his strident approach and offensive rhetoric have taken a toll on his electoral prospects.

“They’re trying to look different in this convention than how they have governed for the last 3 ½ years,” he said. “It’s pretty cynical.”

Trump pulled together a lengthy roster of validators in his four-day nominating convention, with a goal of rebooting his campaign and changing the narrative of a presidency in crisis.

Several family members testified on his work ethic, countering the image of a television-obsessed president who doesn’t read his briefing materials. Lawmakers and residents described him as an empathetic and caring listener behind closed doors, a contrast to his public image as a cruel brawler.

Black supporters declared he was not a racist, national security officials said he was a level-headed commander in chief, and female aides countered the image of a onetime playboy who as president tweets about women’s facelifts and facial features. Several medical professionals described him as a lifesaving leader who successfully responded to the coronavirus pandemic.

The deluge of back-to-back misleading depictions offered a distortion of reality with the sole aim of earning Trump a second term, said Barbara A. Perry, director of presidential studies at the University of Virginia’s Miller Center.

“Our legendary presidents are known for their truthfulness: Washington couldn’t tell a lie, Lincoln earned the moniker ‘Honest Abe,’ Truman was famous for plain speaking,” she said. “So it is indeed ironic that our first reality-TV-star-turned-president, abetted by his party, would bury truth in an avalanche of prevarications about current cataclysms and his role in them.”

The Trump campaign has claimed that the president is only using the platform of the convention to deliver an unfiltered message directly to the American people, blaming the news media for often injecting bias into their coverage of the White House.

“The national news media has turned into the Joe Biden rapid response team, inventing a new role for themselves as the partisan opposition to President Trump,” campaign spokesman Tim Murtaugh said by email. “It’s reached such bizarre levels that the Post even fact-checked Herschel Walker’s (true) statement that President Trump once owned a professional football team. These fact checks are practically the same as press releases from rival political campaigns.”

The Washington Post Fact Checker did not look into whether Trump owned the team but assessed Walker’s assertion that “he used what he learned to make the team better.”

Biden has made Trump’s loose relationship with the truth part of his messaging pitch, saying Thursday that the president’s attacks on him were part of a pattern of stretching the truth and using lies to distract from his record.

“It’s just one lie after the other — lying, lying, lying, lying,” Biden said on MSNBC. He added, “I think everybody knows this man has a somewhat pathological tendency to not tell the truth.”

After Vice President Pence’s speech Wednesday, Biden deputy campaign manager Kate Bedingfield accused Republicans of using “debunked scare tactics and gaslighting in an attempt to further divide us.”

There’s a risk that the approach by Trump could backfire, with polls showing most Americans do not view the president as honest. In a statement endorsing Biden, more than 200 officials from the George W. Bush administration denounced Trump for a lack of honesty.

“Over the past four years we, as a nation, have struggled with truth,” said the statement. “Conspiracy theories have been legitimized and facts have been dismissed.”

The statement took Trump to task for his handling of the pandemic, which the president has received low marks for in public polls as the death toll has surpassed 175,000 Americans.

During the convention, some Trump allies referred to the pandemic in the past tense, and others attempted to rewrite the history of his response.

In glitzy videos and misleading testimonials, Trump was hailed as a bold and lifesaving leader who “was right” on the coronavirus while Democrats and doctors were wrong.

Pence on Wednesday hailed Trump for banning “all travel” from China in January, even though the president’s restrictions had several exemptions and did not stop the virus from spreading through communities.

On foreign policy, Trump’s erratic approach was presented as steady and effective, with former U.S. ambassador to Germany Richard Grenell claiming that he had watched Trump “charm” German Chancellor Angela Merkel and with other officials falsely suggesting that the president has brought back significant numbers of American troops from abroad.

Pence and a number of other speakers stretched the truth as they attacked Biden and predicted he would fail to enforce law and order if he was elected. Trump’s son Eric falsely claimed Biden supported defunding police, Republican National Committee Chairwoman Ronna McDaniel indicated Biden would raise taxes on 82 percent of Americans, and former Notre Dame football coach Lou Holtz described Biden as a “Catholic in name only.”

The Post’s Fact Checker and other independent outlets have debunked those and other claims as misleading or false.

But with four days of largely uninterrupted prime-time messaging, Trump’s attacks could succeed in their intended goal of dragging down Biden’s poll numbers and uniting much of the Republican Party around the president, said Emma Briant, a professor at Bard College who studies propaganda and political communication.

“The RNC seems to have put the emphasis on a tried-and-tested weapon to try and unite support — leveraging fear in fearful times,” she said. “If one doesn’t have truth on one’s side, shouting loudly with emotion can certainly work.”

Jose A. Del Real contributed to this report.