Pope Francis did not plan on meeting with Sanders, and news outlets including the Los Angeles Times reported Friday that he did not.
But on Saturday, Sanders told the Associated Press that he met Francis for about five minutes early that morning as the pope was leaving for a visit to Greece to address Europe's refugee crisis.
Sanders and his wife were staying at the Casa Santa Marta, the Vatican guest house where the pope lives.
Although polls show Sanders trails rival Hillary Clinton in New York, which votes Tuesday, the Democratic senator from Vermont interrupted his insurgent campaign to cross the Atlantic to emphasize the same economic critique that has propelled his candidacy all year at home.
Denouncing a U.S. political system where "billionaires can buy elections," Sanders told the conference that "speculation, illicit financial flows, environmental destruction, and the weakening of the rights of workers is far more severe than it was a quarter century ago."
Addressing a small group in a frescoed villa in the Vatican's manicured gardens, Sanders added, "In the year 2016, the top 1% of the people on this planet own more wealth than the bottom 99%."
Sanders said, "Widespread financial criminality on Wall Street played a direct role in causing the world's worst financial crisis since the Great Depression."
Addressing delegates who included the presidents of Ecuador and Bolivia, Sanders added, "In my country, home of the world's largest financial markets, globalization was used as a pretext to deregulate the banks, ending decades of legal protections for working people and small businesses. Politicians joined hands with the leading bankers to allow the banks to become 'too big to fail.'"
Sanders arrived at Friday lunchtime with his wife and 10 family members, including four grandchildren. The conference commemorated the 25th anniversary of a teaching document by
As Sanders entered the hall, a note sent by Pope
"As you know, I had envisaged coming today, around 7 p.m., to greet the participants of the workshop," he wrote. "Yesterday I realized that today was going to be very complicated because of my trip to Lesbos."
He added, "Today I confirm this situation and would like to apologize for not being able to attend."
Sanders told Italian newspaper La Repubblica on Friday he was a "huge supporter" of the pope, even if he disagreed with Francis' opposition to same-sex marriage.
Sanders denied that he believed his invitation to the Vatican gave his campaign papal backing. Sanders aides have denied the trip was aimed at appealing to Catholic voters in New York.
The pope may have shunned a formal meeting with Sanders to avoid another plunge into this year's U.S. presidential campaign.
In February, Donald Trump called Pope Francis "disgraceful" after the pontiff suggested the Republican front-runner was "not a Christian" for his plan to build a wall along the Mexican border.
Left-wing Bolivian President
Sanders has said he insisted on jumping off the campaign trail for 24 hours because of his fondness for Francis' critique of unbridled capitalism, which the pope has defined as the "dung of the devil."
After warning in 2013 that uncontrolled economies “kill,” Francis has claimed that poor countries should not be forced to provide cheap labor for the rich West, prompting conservative commentator
Sanders referred frequently to Francis' own stand against inequality in his speech, suggesting they shared a common cause.
"As Pope Francis has stated: 'Man is not in charge today, money is in charge, money rules,'" he said. "And the pope has also stated: 'We have created new idols. The worship of the golden calf of old has found a new and heartless image in the cult of money and the dictatorship of an economy which is faceless and lacking any truly humane goal.'"
Sanders added that Francis has "called upon financial executives and political leaders to pursue financial reform that is informed by ethical considerations. He stated plainly and powerfully that the role of wealth and resources in a moral economy must be that of servant, not master."
Rather than giving in to the status quo, Sanders said Pope Francis was an example of someone fighting back.
"Pope Francis himself is surely the world's greatest demonstration against such a surrender to despair and cynicism," he said. "He has opened the eyes of the world once again to the claims of mercy, justice and the possibilities of a better world. He is inspiring the world to find a new global consensus for our common home."