The Archbishop of the Moroccan capital, Cardinal Cristóbal López Romero, has backed the Sumud Flotilla, the largest attempt to breach Israel's blockade of Gaza, stating he would join the fleet "in spirit."
In a video released last week, Cardinal López Romero, a Spanish-born Salesian priest who briefly emerged as a papal contender after the death of Pope Francis, called the flotilla "an act of solidarity, courage and commitment."
From Rabat, he urged the public not to remain "anchored in indifference" but to join the effort.
"I want to stand in solidarity, personally and institutionally, with this effort to seek peace and denounce injustice," he said, offering his blessing and prayers for the safety of the activists.
More than 50 boats are expected to depart from Tunisia on Sunday and from other Mediterranean ports, carrying humanitarian supplies to Gaza in defiance of a blockade Israel has enforced for more than 17 years.
Organisers describe the mission as civilian and nonviolent, with no government backing, though they hope the presence of world leaders, religious figures, and celebrities will help protect participants.
The Global Sumud (previously written as Somoud) Flotilla takes its name from a land convoy that set out from Tunis in June but was forced to turn back after being intercepted near Sirte by forces loyal to Libyan warlord Khalifa Haftar.
This time, Tunisia's Coordination for Joint Action for Palestine has joined forces with the Freedom Flotilla, Global Freedom to Gaza, and Asia's Sumud Nusantara to launch what they call the largest maritime effort yet.
High-profile figures have rallied behind the voyage.
Colombian President Gustavo Petro sent a letter of solidarity, calling it "a living testimony of humanity that still rises in the face of barbarism."
Malaysia's Prime Minister Anwar Ibrahim has pledged to join, while Greta Thunberg, the Swedish climate activist, will sail alongside Irish actor Liam Cunningham, Spanish actor Eduardo Fernández, and former Barcelona mayor Ada Colau.
Organisers say the convoy will ultimately surpass the combined size of all earlier flotillas.
Israel has scuppered numerous attempts over the 15 years of the blockade, including a 2010 boarding by its special forces in which at least nine Turkish activists were killed.
But this time, participants say, the sheer scale and international breadth of the mission make it harder to stop.
"I don't think they will be able to stop us," Ayoub Harbaoui, a Moroccan activist set to join the flotilla, told The New Arab.
"We are hundreds of activists. We believe we will reach Gaza this time. Even if stranded at sea, we are carrying enough supplies to survive for a month."
Israeli officials have vowed to prevent the convoy from reaching Gaza.
National Security Minister Itamar Ben-Gvir presented a plan to the cabinet over the weekend to halt the flotilla, threatening to detain participants in "terrorist prisons" for extended periods so that "supporters of terror would think twice before attempting another such flotilla."
The activists' call for moral authority has extended to the Vatican itself. Some activists have urged Pope Leo XIV to join the fleet, with American singer Madonna lending her voice to the appeal. The Holy See has not responded.
Cardinal López Romero, who hails from Vélez-Rubio in southern Spain, has maintained a prominent role under Pope Leo, who appointed him to the Vatican dicastery overseeing religious orders.
In his message, the cardinal framed the voyage not just as a humanitarian mission but as a moral reckoning.
"This is an awakening for all societies, (...) to the injustice being committed against the Palestinian people," said the cardinal.