Pete Buttigieg has described how his Maltese father was told to 'go home' because of his 'brown skin' and 'unique accent' during an anti-apartheid protest.
Mr Buttigieg told the story after US president Donald Trump launched a crackdown on illegal immigration and said a group of congresswoman should go back to where they came from.
The 37-year-old mayor of South Bend, Indiana, is vying to become the 2020 Democratic presidential nominee.
His late father, Joseph Buttigieg, was from the Ħamrun area of Malta but emigrated to America in the late 1970s.
In a tweet, Mr Buttigieg described an experience his father had endured.
"As an immigrant and a citizen, my dad cared deeply about this country," he wrote.
"Once, when he was speaking at a campus protest against Reagan’s accommodation of apartheid, a passing student noticed Dad’s brown skin and unique accent and called out: 'go home!'
"He answered: 'I am home.'"
The tweet provoked a mixed response. Many people questioned whether skin colour was an issue in the case.
However, others praised Mr Buttigieg for sharing his story and responded with their own cases of intolerance against immigrants.
Mr Buttigieg entered the race to become the Democratic candidate for the 2020 US Presidential election in January.
If he is successful, he would be the youngest ever and first openly gay man to be commander in chief.
He started the race as a rank outsider but last month gained momentum when he raised the most funds of any Democratic candidate in the second quarter.
Did you know the Buttigieg family when they lived in or visited Malta? Share your stories by emailing firstname.lastname@example.org with the subject 'Pete Buttigieg'.