But at a low-key rally in Manchester, New Hampshire, on Thursday, Trump supporters said there's no xenophobic subtext to the phrase — at least not the way they see it.
Keith, who declined to give his last name and runs a landscaping company in Massachusetts, said, "I think that we need to support one another and the nation we live in. You gotta give back."
"To me that means doing charity," he added. "But people who aren't doing that got to pay taxes. You can't be undocumented. That's what America First means."
Trump has come under fire during the course campaign for rhetoric that critics say favors American-born whites. Hillary Clinton ratcheted up that criticism in a speech Thursday attempting to tie Trump to the so-called "alt-right" movement that generally espouses white supremacy.
Trump, Clinton said, has helped "mainstream" racist hate groups.
But the developer, speaking shortly before Clinton, tried to preemptively deflect the attack at his rally.
"This is a movement we have," Trump said. "It's the oldest play in the Democratic playbook. When democratic policies fail, they are left with only this one tired argument. You're racist. You're racist. You're racist. They keep saying it. You're racist. It's a tired, disgusting argument. And it's so totally predictable."
He told supporters in the half-full hotel auditorium in Manchester that they shouldn't fear being branded "racists" for supporting tougher policies on borders and refugees.
Diane Lord, a retiree from New Hampshire, said "America First" has nothing to do with race.
"'America First' means take care of your own," said Lord, who was among the first in line to enter the auditorium. "Refugees and overseas later, fine. But Americans should come first."
Lord, a retiree, said she hoped Trump would protect the financial security of senior citizens like her instead of focusing on foreign issues.
Patty Tremblay, who drove to the rally from Massachusetts, had a similar view on "America First."
"I interpret it as citizens need to be first, not people who are coming illegally," she added. "People who are working in America or retired, they should be first, no one else."
But it's also about a feeling of safety, she added.
"I care about security. I want to be safe," Tremblay said. "That means security of the border."
And Nancy, from Hampton, who also refused to give her last name, said, “the black community is also waking up — if they’ll give Donald Trump a chance. It’s for everybody, including them."
"That’s what America First means," said the retiree, who is white. "It isn’t about race and skin color. The media sickens people because of making it about that."
Several Trump supporters who spoke to BuzzFeed News said though they had no problem with the slogan America First, it didn’t mean much to them.
"That’s not what I’m voting on,” said Hank, who refused to provide his last name. “What I care about is that he can bring success in lifting up inner cities. None of the Democrats have done that."