The Vatican urged Maduro "to suspend ongoing initiatives such as the new Constituent Assembly, which, rather than fostering reconciliation and peace, encourages a climate of tension and confrontation and mortgages the future."

In a statement, the Archbishop Oscar Romero U.S. Centennial Commission said it invites churches "to honor Blessed Romero by including a petition or other remembrance during Assumption Day Masses."

"The bishops are unanimous in their rejection of this new assembly, and we are asking the government to reconsider," Cardinal Urosa told Venezuela news station Globovision the day before the vote.

Electoral authorities said more than 8 million people voted Sunday to create a constitutional assembly endowing President Nicolas Maduro's ruling party with virtually unlimited powers—a figure widely disputed by independent analysts.

Days before a referendum to elect a constituent assembly to rewrite Venezuela's constitution, leaders of the country's bishops' conference said the referendum is illegal and will only increase the suffering of the people.

Rome is urging Venezuela President Maduro and his Chavistas to hold the elections they are now blocking, release hundreds of political prisoners like Mr. López and restore the democratic separation of powers they have mowed down.