Donald Trump Jr. addresses the Republican National Convention on July 19. (Jabin Botsford/The Washington Post)

With 42 words, a hashtag and a bowl of Skittles, Donald Trump Jr. set out to illustrate what he saw as the danger of letting Syrian refugees into the United States. Instead, he set the Internet ablaze with controversy.

In a tweet, the Republican presidential nominee’s eldest son equated refugees with a bowl of the colored candy that included some pieces that had been poisoned. The blowback was immediate and widespread Tuesday, as many critics said the message belittled refugees and was bigoted. Even the maker of Skittles rebuked him.

The reactions highlighted a recurrent subplot in this year’s presidential campaign: Trump Jr. has repeatedly sparked controversy by associating himself with ideas, themes and people seen as racially or culturally charged.

In some cases — such as when he did a radio interview with a white nationalist and posted a symbol used by white supremacists — Trump Jr. claimed ignorance. Still, some have found his actions nearly as troubling as the blunt attacks his father has launched against individuals and groups he dislikes.

Fergus Cullen, a New Hampshire-based Republican strategist who does not support Donald Trump’s campaign, said he was “disgusted” at the way Trump Jr. and others have spoken disparagingly about refugees. “Talk about a politically powerless group with no public defenders,” Cullen said. He also decried the “frat boy” culture around Trump, which he said stems directly from the candidate.

Donald Trump Jr. tried to make a political point about refugees on Twitter on Sept. 19, but he got it all wrong. The Fix's Philip Bump explains how. (Peter Stevenson/The Washington Post)

In a statement Tuesday, Trump campaign spokesman Jason Miller defended Trump Jr., calling him a “tremendous asset” to the team.

“Here’s the reality: this is a family that’s passionate about changing America by bringing real positive change to Washington,” Miller said. “They’re not political insiders, and their honesty and connection with real people is what’s made them so popular with voters also seeking change.”

The flap over Trump Jr.’s tweet could further complicate his father’s intensifying effort to appeal to centrist Republicans, independents and Democrats. Word this week that Republican former president George H.W. Bush plans to vote for Hillary Clinton also made things more difficult. Kathleen Kennedy Townsend, a Democratic former lieutenant governor of Maryland, said Bush told her of his choice Monday.

The GOP nominee has been a vocal critic of Clinton and President Obama’s welcoming of Syrian refugees into the United States, voicing alarm that doing so could bring in terrorists determined to attack Americans. Trump has made halting the flow of Syrian refugees into the country a centerpiece of his campaign.

On Monday afternoon, Trump Jr. opined on the subject by tweeting the image of the candy and an accompanying question that he argued “said it all”: “If I had a bowl of skittles and I told you just three would kill you. Would you take a handful?”

The answer to the question was: “That’s our Syrian refu­gee problem.” Trump Jr. added: “Let’s end the politically correct agenda that doesn’t put America first. #trump2016”

Donald Trump Jr., son of Republican presidential candidate Donald Trump, has drawn a sour rebuke from the maker of Skittles after he compared Syrian refugees to poisoned candy. (Reuters)

The tweet drew a swift and intense backlash.

“Skittles are candy. Refugees are people. We don’t feel it’s an appropriate analogy,” Wrigley, the parent company of Skittles, said in a statement sent by its vice president of corporate affairs, Denise Young. “We will respectfully refrain from further commentary as anything we say could be misinterpreted as marketing.”

Clinton campaign spokesman Nick Merrill retweeted Trump Jr.’s message, calling it “disgusting.”

David Kittos, a British citizen who said he took the Skittles photograph six years ago, told the BBC he is a refugee who left the Turkish occupation of Cyprus as a young child. He said he does not endorse Trump Jr.’s use of his photo. “This was not done with my permission, I don’t support his politics, and I would never take his money to use it,” he said.

Some noted problems with the scale of the analogy embraced by Trump Jr. The Cato Institute, a libertarian think tank, published a report last week finding that, each year, the risk to an American of being killed by a refugee in a terrorist attack is 1 in 3.64 billion — a far cry from the three-in-a-bowl notion expressed in Trump’s tweet.

The analogy does not appear to be a Trump Jr. creation. Former congressman Joe Walsh, an Illinois Republican, wrote on Twitter that he made the same point in August. The candy meme has also been used before to make different points.

Last week, Trump Jr. told WPHT radio in Philadelphia that the media has been Clinton’s “number one surrogate,” letting her slide “on every indiscrepancy, on every lie, on every DNC game trying to get Bernie Sanders out” of the way. He added, “If Republicans were doing that, they’d be warming up the gas chamber right now.”

For that remark, he faced criticism from the Anti-Defamation League and the campaigns of Clinton and independent candidate Evan McMullin. McMullin took to Twitter to call it an “unsurprising Nazi reference from the ‘alt-right’ movement’s presidential campaign,” referring to the name adopted by many white nationalists online. Trump Jr. told ABC News he used a “poor choice of words.”

In March, Trump Jr. drew scrutiny when white-nationalist radio host James Edwards aired an interview with him. Trump Jr. later told Bloomberg he did not realize that Edwards was going to be looped into an interview he was doing with another host.

Earlier this month, Trump Jr. posted an image on Instagram he said he got from a friend that was meant to draw attention to Clinton referring to “half” of his father’s supporters as “a basket of deplorables.” The image included Trump and a number of his supporters. It also included Pepe the Frog, a cartoon figure that has been appropriated by white supremacists. He told ABC News he did not know about the association.

Trump Jr. plays an active role in his father’s campaign. The 38-year-old father of five is also executive vice president at the Trump Organization.

During a breakfast event hosted by the Wall Street Journal on the sidelines of the Republican National Convention in Cleveland, Trump Jr. expressed openness to one day following in his father’s footsteps and running for public office.

Jenna Johnson, Aaron Blake, John Wagner and Philip Bump contributed to this report.