Why do Trump and allies repost racist messaging and will it help his reelection effort?

Amid historic nationwide protests calling for racial justice, President Donald Trump retweeted a video last Sunday showing a supporter yelling "white power!"

Then, more than three hours and thousands of views later, the tweet was deleted and the White House issued a statement claiming the president "did not hear" what the supporter could clearly be heard saying.

As startling as it was, it was only the latest instance of the president using his vast social media presence to magnify racist messaging to a segment of his political base, ahead of the November election.

One critic says it's part of a growing pattern on the part of Trump, his campaign and allies to push racially inflammatory language and then, after widespread outrage, claim ignorance.

Leah Wright Rigueur, professor of public policy at the Harvard Kennedy School and author of "The Loneliness of the Black Republican," calls that pattern "convenient."

"If it was actual ignorance, we wouldn't see this happening repeatedly and we also wouldn't see the same kind of targeted type of retweets, tweeting commentary, etc. So, it just seems like a very convenient shield as defense to use, when once again they find themselves in the position that they're often in," Rigueur told ABC News.

Days after he retweeted the "white power" clip, despite criticism from even members of his own Republican Party, the president had yet to condemn the racist message he had promoted.

The White House said deleting the tweet was enough.

"The president did not hear that phrase in that portion of the video, and when it was signaled to him that this was in there he took that tweet down, White House press secretary Kayleigh McEnany said in a Fox News interview on Monday, adding that the president shared the video featuring the racist phrase to "stand with his supporters who are oftentimes demonized."

The pattern goes beyond the president's own words and actions.

Earlier in June, senior Trump campaign adviser and former White House aide Mercedes Schlapp shared a disturbing video on her Twitter page featuring a man wielding a chainsaw and yelling the n-word while chasing away demonstrators protesting the killing of George Floyd in Minneapolis police custody.

Schlapp later claimed she did not hear the racist language that appears immediately in the clip.

"I deeply apologize and I retweeted without watching the full video," Schlapp said in a statement to ABC News.

And Facebook last month removed multiple Trump campaign ads that featured symbols similar to those used by Nazis in concentration camps to denote political prisoners, liberals and communists, among others.

Just two days after the president shared the "white power" video, Trump campaign senior adviser Katrina Pierson posted a racist meme on her personal Instagram account on Tuesday that called Rep. Ilhan Omar, a Minnesota Democrat and the first Somali refugee elected to Congress, a "terrorist."

In the image, Omar is featured saying she hates Trump, with the president replying, "most terrorists do."

The Trump campaign did not respond to a request for comment.

All this comes after Trump, in late May, at the height of the George Floyd protests, tweeted, "Just spoke to Governor Tim Walz and told him that the Military is with him all the way," he continued, "Any difficulty and we will assume control but, when the looting starts, the shooting starts."

The phrase "when the looting starts, the shooting starts" originated in 1967, at the height of the civil rights movement, when Miami Police Chief Walter Headley used it speaking about violent crime in the segregated city.

He boasted that Miami hadn't "faced serious problems with civil uprisings and looting because I've let the word filter down that when the looting starts, the shooting starts," according to the Miami Herald.

Headley became known for bearing down particularly hard on communities of color with policing policies such as stop-and-frisk and use of patrol dogs.

When asked why he used the same phrase, Trump said he wasn't aware of its history. "I've heard that phrase for a long time. I don't know where it came from or where it originated," Trump said, adding, "I've also heard from many other places. But, I've heard it for a long time, as most people have."

Twitter placed a warning on his tweet, saying it "violated the Twitter Rules about glorifying violence." But it was not taken down by the social media company because, according to Twitter, it "may be in the public's interest for the Tweet to remain accessible."

Charles Chamberlain, executive director of Democracy for America, told ABC News he believes Trump and his allies are doubling down on racist messaging in order to reach a core group of supporters who've backed him throughout his presidency, saying "that coalition is fueled by racism and fear."

Chamberlain said it's a key reason Trump won in 2016.

"They were able to mobilize the racist base in the Republican Party," he said, arguing it continues to be a central part of their strategy in 2020.

The recent controversies come as Trump's polling averages show him down 9 points nationally to former Vice President Joe Biden, according to FiveThirtyEight.

In a recent New York Times/Siena poll, Biden leads Trump by 14 points, with 50% of registered voters saying they would support him if the election were held today.

In that same poll, Biden has a commanding lead among minority voters. Black voters overwhelmingly support Biden at 79%, while Trump is at 5%. For Hispanic and Latino voters, Biden currently sits at 64% while Trump at 25%.

But beyond reinforcing racist views within his base, the messaging would seem to have little chance of winning over new voters he needs.

Unlike Chamberlain, Rigueur says she doesn't think sending racist messages -- and then claiming ignorance -- is a part of a strategy to energize the base but rather, she maintains, it's "a reflection [of] his gut instincts."

And in a tight election, she argues, the racist language makes it harder for those Black voters who do support Trump to defend him moving forward.

"There's no amount of explaining away that a Black supporter of Trump can do even on social media, that would justify that, so it makes it really hard, especially makes it a really hard sell," Rigueur said. "I think that, you know, that discrepancy or that dissonance, is actually going to be really important moving into the 2020 election. You don't have coverage anymore."

These inflammatory comments also could drive a wedge between his staunch supporters and the moderate voters who back some of the president's policies, as some may be wary about being associated with such messages when the country is in a moment of soul searching on issues of race.

Chamberlain said these incidents aren't exclusive to the president's time in the Oval Office, saying they happened during his 2016 presidential campaign.

"He started with dog whistles like questioning (President Barack) Obama's birth certificate, to outright racist attacks like calling Mexican immigrants rapists and criminals. That's how he started his campaign. Then over the last four years all we've seen is more and more of that. ... I wouldn't call it a pattern, I would call it the foundation of the Trump presidency," said Chamberlain.

In November 2015, then-candidate Trump, retweeted a photo of inaccurate crime statistics showing a disparate rate of "black-on-black" crime, which has often been touted as a retort to the Black Lives Matter movement.

In an interview with then Fox News host Bill O'Reilly, Trump said, "Am I going to check every statistic? I get millions and millions of people @realdonaldtrump by the way," Trump continued, "All it was is a retweet, it wasn't from me."

In July 2016, Trump tweeted a photoshopped image of Hillary Clinton in front of a background of cash, juxtaposed to a red Star of David, reading "Most Corrupt Candidate Ever."

The tweet was blasted as anti-Semitic and then later deleted. It was then tweeted again without the Star of David. Critics said linking the two images of money and the Star of David were a nod to the anti-Semitic trope that Jewish people only care about money.

Then-Hillary Clinton's director of Jewish outreach for her 2016 campaign said in a statement that "Donald Trump's use of a blatantly anti-Semitic image from racist websites to promote his campaign would be disturbing enough, but the fact that it's a part of a pattern should give voters major cause for concern."

The Trump campaign then did not immediately reply to ABC News for comment. However, Trump later told CNN that, "These false attacks by Hillary Clinton trying to link the Star of David with a basic star, often used by sheriffs who deal with criminals and criminal behavior, showing an inscription that says 'Crooked Hillary is the most corrupt candidate ever' with anti-Semitism is ridiculous.'"

The president's eldest son is also sparking controversy with his own social media posts.

During the Democratic primary, Donald Trump Jr. posted a tweet questioning California Sen. Kamala Harris' race and whether she was an "American Black." It was met with widespread backlash by many of her supporters and fellow candidates who called the tweet racist and ugly.

A spokesman for Trump Jr. told ABC News in June 2019 that "Don's tweet was simply him asking if it was true that Kamala Harris was half-Indian because it's not something he had ever heard before."

"And once he saw that folks were misconstruing the intent of his tweet he quickly deleted it," the spokesman said.

In response to the president's "white power" retweet, John Cohen, an ABC News contributor who previously served as acting undersecretary for intelligence at the Department of Homeland Security, said, "he has a tendency to post or say things that are either inaccurate, inflammatory and sometimes they can even be dangerous because they incite people to violence."

Cohen told ABC News that if the president and his allies just did this one time, it could be seen as a mistake. "This White House has on multiple occasions mimicked the language and rhetoric of white supremacist thought leaders," he said.

This past week, just days after retweeting the "white power" video, Trump continued to inflame racial tensions. On Wednesday, he blasted New York City Mayor Bill de Blasio's plan to paint the words "Black Lives Matter" on the street outside Trump Tower, calling it a "symbol of hate" and said that "maybe" the police might stop it from happening.

The president responded on Twitter to an interview in which Hawk Newsome, president of the Greater New York City Black Lives Matter chapter, said, "If this country doesn't give us what we want, then we will burn down this system and replace it."

Trump responded by calling that "Treason."

While it remains to be seen whether the president's racial messaging through retweets and reposting will work, many corporations have backed the Black Lives Matter movement, announcing their support -- via social media campaigns.