Conservatives within the church long blocked efforts to name Romero a saint, arguing he was slain for his politics, not his religion. They disliked Romero's embrace of liberation theology, a church movement that argued that while clergy should care for the poor, they should also push for political changes to end poverty, with some priests even supporting armed struggles.
Francis, a Jesuit from Argentina who became pope in 2013, has made Romero's ascension a priority. He cleared the way for him to be beatified in 2015 and now for canonization, the last step to sainthood.
Normally, candidates for sainthood have to be attached to two miracles. In Romero's case, however, he is declared a martyr -- killed for his faith -- which means only one miracle had to be attributed to him.
The miracle that cleared the way for Romero's sainthood concerned the medically inexplicable cure of a pregnant, terminally ill Salvadoran woman who was "condemned to death" by illness but lived, and gave birth to a healthy child, Archbishop Vincenzo Paglia, a Vatican official, told the Associated Press.
The woman's husband first began praying to Romero in May 2015 when the priest was beatified in San Salvador, Paglia said. By late August or early September, the woman's condition had worsened, and her doctors delivered the child fearing that he too would die.
"They did the caesarean and were waiting for her to die," because all the tests indicated she wouldn't survive. Paglia didn't specify the illness. Her friends started praying to Romero "and after five days, in an inexplicable way, this woman begins to improve and was completely healed."
Paglia said he hoped Romero and Pope Paul VI would be declared saints together in October, saying a joint canonization would give Catholics a "burst" of energy and example of the need to live one's life for others.
"I'm in a hurry because there's an urgent need to change the world," Paglia told AP. "It has been a long, tortuous journey, full of obstacles and opposition," he said. "But it has finally reached its conclusion."
Father Tom Reese, an analyst at the National Catholic Reporter, said Wednesday's announcement "shows first and foremost that Pope Francis really liked and admired Oscar Romero."
"To Francis, he was a bishop who cared for the poor and marginalized and was prepared to lay down his life for them," Reese said. "That is the kind of bishop Francis wants, that is the model, and that is his message for bishops in Latin America."