Frida Ghitis, a former CNN producer and correspondent, is a world affairs columnist. She is a frequent opinion contributor to CNN and The Washington Post and a columnist for World Politics Review. The opinions expressed in this commentary are those of the author; view more opinion articles on CNN.

(CNN) Donald Trump's grandfather, Friedrich Trump, was born in Kallstadt, Germany, and emigrated to the United States as a teenager. (According to one historian, he was thrown out of his country of birth for failing to perform mandatory military service.) Now Friedrich's grandson has become President of the United States, and is trying to fuel a re-election campaign by stoking nativist resentment.

On Sunday morning, Trump tweeted what you might call the unofficial launch of his 2020 dog-whistle re-election campaign.

It was so inflammatory that it burnt through the hesitations of cautious editors. CNN plainly, correctly, called it a "racist attack." The President sarcastically suggested that some of his non-white critics are not real Americans. He urged that "Progressive Democrat Congresswomen," the best-known of whom happen to be women of color, should go back to their countries. The "Congresswomen," he wrote, "who originally came from countries whose governments are a complete and total catastrophe, the worst, most corrupt and inept anywhere in the world..." should leave.

He was most likely referring to Alexandria Ocasio-Cortez, born in New York; Rashida Tlaib, born in Michigan; Ayanna Presley, born in Massachusetts; and Ilhan Omar, a Somali-born naturalized American. They are all US citizens, like him, like his wife , his in-laws, and his ex-wives. They are Americans.

Perhaps I'm overly optimistic, but I think Trump has Americans pegged wrong. This electoral strategy will backfire.

The America I have known is made up primarily of people who are intrigued and attracted to people of different backgrounds.

And although there has always been a segment that does not trust outsiders -- and bigots who consider non-whites inferior -- most Americans are not racists, not bigots, and not nativists. So why is Trump, the man who possesses a peculiar political instinct, betting his re-election on dividing Americans and turning them against their better instincts?

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He thinks it worked the first time. But this is not 2016. In 2016, the entire world was terrified by ISIS terrorists beheading hostages and blowing up nightclubs. The Great Recession was recent enough that people still feared the recovery might unwind, making it easier for many people to believe that immigrants were taking away their jobs. He could frighten people by talking about rapists at the border, promising better health care, and an administration of "only the best people." Back then, we didn't know quite how much Trump lied, and how many of his promises he would be unable to keep.

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It's different now. Trump's dog-whistle, formerly perceived mainly by extremists, is now a trumpet we can all hear.

Sure, his racism, his cruelty against migrants and his family separation policy will still play well with a segment of the electorate. But today, Americans see Trump for what he is. They see his campaign and what he is trying to do. When he tweets about corrupt, inept governments, we think about Donald Trump. When he tells the descendants of immigrants that they should leave, we think perhaps Friedrich Trump's grandson is the one who doesn't belong here.