MADRID — After a tight vote, politicians often squabble over how to form a coalition government. But the argument that has followed regional elections in Catalonia is more fundamental than most.

It is not yet clear who could physically lead the next administration in Spain’s restive region: The coalition talks involve party leaders who are either in self-imposed exile or in jail.

Spanish judges may have the final say, as they determine whether separatist politicians are eligible for office even as they await trial on charges of sedition and rebellion brought after they unilaterally declared Catalonia’s independence in October.

On Friday, the Spanish Supreme Court rejected an appeal by Oriol Junqueras, leader of the separatist Esquerra Republicana party, who was seeking to post bail after two months in a Madrid prison.