The USA Freedom Kids' performance act went viral within hours of performing at a Donald Trump rally.
Online viewers gawked at the three pre-teen performers in star-spangled outfits as they lipsynched their way through a song in praise of the billionaire businessman.
Mr Trump was so impressed that he told the group he planned to listen to their CD all night, according to Inside Edition,
Yet the father of the youngest Freedom Kid and the creator of their song, Freedom’s Call, Jeff Popick, plans to sue Mr Trump after he allegedly violated their verbal agreement.
"This is not a billion-dollar lawsuit," Mr Popick told The Washington Post.
"I'm doing this because I think they have to do the right thing. And if this means having to go through the court system to enforce them doing the right thing, then that's what I have to do. I'm not looking to do battle with the Trump campaign, but I have to show my girls that this is the right thing."
The lawsuit is another in a long line of legal battles facing the Republican nominee, including allegations of sexual harassment and fraud around his now defunct Trump University. Mr Trump also filed a $10 million lawsuit himself after his former adviser, Sam Nunberg, who allegedly leaked information about Mr Trump's campaign.
Mr Popick claims that Freedom Kids was offered two rally performances in Florida, but only the second one in Pensacola came to fruition, and a counter-offer of a table to sell albums to compensate for the first gig was not available.
He also said he paid to travel to Iowa for a last-minute offer to perform in Des Moines, but was only told of the change in plan after the children and their parents arrived at Chicago airport. Instead of performing, they attended the rally and were told not to speak to the press.
Further attempts to resolve Mr Popick's grievances with the Trump campaign were not successful, he said.
He claims he is owed compensation or a performance, as was the verbal agreement, and has consulted a lawyer.
"I've invested a lot of time, effort, money," he told the paper, "and it's just been complete silence."
Mr Popick admitted he has more lukewarm feelings now about whether Mr Trump would make the "best candidate" for president.
The group’s album, Freedom’s Call, will be out in September, but will not include the original line: "President Donald Trump knows how to make America great".
Mr Trump's campaign could not be reached for comment.
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