Spain's King Felipe was greeted by hundreds of chanting protesters during a visit to Catalonia on Monday as pressure mounted on him in Madrid to respond to corruption allegations swirling around his father, former King Juan Carlos.
While the demonstrators squared off with police and shouted "We don't have a king" as Felipe and Queen Letizia visited a monastery near Tarragona, ministers are demanding action amid calls for a parliamentary investigation.
In June, Spain's Supreme Court opened an investigation into Juan Carlos' involvement with a high-speed rail contract in Saudi Arabia after Switzerland's La Tribune de Geneve newspaper reported he had received $100 million from the late Saudi King.
Through his lawyer, Juan Carlos, 82, has repeatedly declined to comment on the allegations.
The newspaper added that Juan Carlos later gave $65 million to Corinna zu Sayn-Wittgenstein, a businesswoman with whom he had a relationship that led to his abdication in 2014. Her representatives have said she's done nothing wrong.
Juan Carlos was popular for his role in the country's transition to democracy in the late seventies, before various scandals eroded public approval a decade ago and forced him to pass the throne to his son.
This time, the focus is on the rail contract affair.
"We want a pretty intense investigation into the activities of the citizen Juan Carlos de Bourbon," Consumer Affairs Minister Alberto Garzon, of the leftist Izquierda Unidad party, told reporters on Monday, referring to the former king.
A government source told Reuters that the cabinet "expects some gesture from King Felipe, something that will distance his father even more from the Royal House." "The options are various ... It's something that must be decided by the royal house.
Looking for a way out of the (royal family's) Zarzuela palace, as some media have said, may be an option. The decree of abdication could also be studied to reduce privileges. Whatever it is must be announced now, imminently."
Another option raised by Spanish media is whether Juan Carlos could lose the title of King Emeritus, which he has had since abdicating following outrage over a secret luxury elephant-hunting trip and a corruption scandal centred on his daughter and her husband.
The monarchy itself, or any change in the constitution, is not at stake at this stage, experts said. There is no majority for that in the Spanish parliament and the constitution gives the former king immunity for his time on the throne.
Javier Perez Royo, professor of Constitutional Law at the University of Seville, said it was "science fiction" to think the constitution could be changed.
He said one possibility would be for Felipe to tell his father to leave palace and stop being a member of the royal household. But voters were likely to want more than that, so no immediate resolution of the problem was in sight.
The Royal House and a representative for Juan Carlos did not immediately respond to requests for comment. They have repeatedly refused to comment in recent weeks.
A friend of Juan Carlos, Jaime Carvajal Urquijo, said on Twitter: "The government's pressure on Felipe VI to take action against his father, without waiting for the courts to rule and without respecting the presumption of innocence, is outrageous!"
In mid-March, when latest the corruption allegations surfaced, Felipe had already renounced any inheritance from his father and ended the former king's palace allowance.