The Spanish Cup finalists Real Sociedad and Athletic Bilbao said on Monday that they had asked the Spanish football federation (RFEF) to ensure the final was played with fans in the ground.
The clubs said in a joint press release that they had met with Luis Rubiales, the president of the RFEF, who had agreed to ask the general assembly on May 8, if the final could be played with open doors.
This would be the first all-Basque final in the history of the competition.
"The desire and will of both clubs has always been, now and before, to play and enjoy the final match along with the supporters," they said in a joint English-language press release.
"This is what we would like most. A final to be lived with our supporters in the stands."
Even so, the two Basque clubs said they wanted guarantees that "the final will be played as an official competition and will, therefore, be considered an official title."