Mickey Joe Harte, Ireland's Eurovision representative this year, is to meet officials at the US embassy in Dublin today in an attempt to obtain a work visa.
He wishes to perform at a charity concert planned for the Gaelic Grounds in New York on Saturday.
His party of 14 - which included his band along with another Donegal group, The Revs - were barred yesterday from boarding a flight to the US at Shannon Airport.
Although they stressed they were not making money from the gig, an immigration official ruled they would require a work visa.
Mr Harte said they were "devastated and very disappointed" about what had happened.
"It all boils down to the fact that a fee is being charged to get into the concert and this generates income so we have to get a work visa," he explained.
The group had been travelling as visitors to the United States. He added that it is "looking unlikely" that the matter can be resolved before the weekend. "Time is against us and there is a lot of red tape.
"We will have to go through an interview process and get photographs and there is a lot of form filling."
News that the concert is now in doubt has come as a major blow to the family of Letterkenny man Mr Mickey Duffy.
The 63-year-old cancer patient has already undergone five operations in the US this year and has run up medical bills in excess of $100,000.
Donegal emigrants in New York have rallied around his cause and tickets were reported to be selling well.
They hoped to raise over $40,000 from the concert.
Mr Duffy's daughter, Jackie, said that they were "gutted".
A number of politicians have taken up the issue with embassy officials and hope that the matter can be resolved to enable the group to fly out on Friday in time for the concert.
"There is a lot of bureaucracy in such matters but I cannot see why it cannot be done particularly when it is such a humane cause," commented Donegal South-West TD, Mr Dinny McGinley.
Mr Frank Fahey TD also said he would raise the matter with the US embassy and Foreign Affairs here. "We facilitate the US when they ask for assistance but here they are treating us like an enemy nation," he added.