"Mister Charlie Lindbergh, he flew to old Berlin
Got 'im a big Iron Cross, and he flew right back again
To Washington, Washington
Misses Charlie Lindbergh, she come dressed in red
Said: "I'd like to sleep in that pretty White House bed
In Washington, Washington"
Lindy said to Annie: "We'll get there by and by
But we'll have to split the bed up with Wheeler, Clark, and Nye
In Washington, Washington"
Hitler wrote to Lindy, said "Do your very worst"
Lindy started an outfit that he called America First
In Washington, Washington" ("Lindbergh", Woody Guthrie)
The current rhetoric of "America First" may seem innocuous to some, even patriotic. But a few generations ago, it was much more than that. As the words of Woody Guthrie, written above, chronicle, the slogan was used by a Hitler backed isolationist initiative to keep the USA out of the war until Hitler's plans could be more fully developed. "Lindy" was one of the most popular people around the world at the time, and the idea was that he could be instrumental in the rise of the Third Reich.
Prior to that, its use as a slogan among the KKK was well established, as seen in the linked parade photo from the 1920's (source: https://www.gettyimages.com/detail/news-photo/ku-klux-klan-stages-an-america-first-parade-in-binghamton-news-photo/514702614#binghamton-ny-ku-klux-klan-stages-an-america-first-parade-in-ny-picture-id514702614). While it is, of course, not necessarily true that the current administration harbors such feelings, it is nonetheless true that a close examination of history reveals a less than wholesome usage of the phrase.