Bernie Sanders issued a global call to action at the Vatican Friday to address "immoral and unsustainable" wealth inequality and poverty, using the high profile gathering to echo one of the central platforms of his presidential campaign.

The Democratic senator from Vermont cited Pope Francis and St. John Paul II repeatedly during his speech to the Vatican conference commemorating the 25th anniversary of a landmark teaching document from John Paul on social and economic justice after the Cold War.

Sanders arrived in Rome hours after wrapping up a debate in New York Thursday night, saying the opportunity to address the Vatican conference was too meaningful to pass up. The roughly 24-hour visit precedes Tuesday's crucial New York primary, which Sanders must do well in to maintain any viable challenge against Democratic front-runner Hillary Clinton.

He told the audience of priests, bishops, academics and two South American presidents that rather than a world economy that looks out for the common good, "we have been left with an economy operated for the top 1 percent, who get richer and richer as the working class, the young and the poor fall further and further behind."

During a discussion later in the afternoon, Sanders was peppered with questions from academics and ecclesiastics at the conference, giving the presidential hopeful a chance to expand on his core campaign messages about the need to reform banking regulations, campaign finance rules and higher education.

"We don't choose to politicize the pope," Sanders told attendees, "but his spirit and courage and the fact, if I may say so here, that his words have gone way, way, way beyond the Catholic Church."

Earlier, Sanders warned that youth around the world are no longer satisfied with the status quo, which includes "corrupt and broken politics and an economy of stark inequality and injustice."

"They are not satisfied with the destruction of our environment by a fossil fuel industry whose greed has put short term profits ahead of climate change and the future of our planet," he said. "They are calling out for a return to fairness; for an economy that defends the common good by ensuring that every person, rich or poor, has access to quality health care, nutrition and education."

He sat next to the other main guest of honor at the Vatican: Bolivian President Evo Morales, whose is renowned for his anti-imperialist, socialist rhetoric.

As he walked through Vatican City's Perugino gate, Sanders was greeted about two dozen supporters, some of whom carried signs bearing Sanders' name.

The senator told reporters that he was honored to address the conference and admired Francis' message on the economy and the environment.

"I know that it's taking me away from the campaign trail for a day but when I received this information it was so moving to me that it was something that I could just simply not refuse to attend," he said.

Pope Francis apologized that he couldn't personally greet participants at the Vatican conference. No meeting with Sanders was expected.

Sanders was accompanied on the trip by his wife, Jane Sanders, and 10 family members, including four grandchildren.

The conference was organized by a Vatican advisory group comparable to a think-tank that Francis appointed to guide him on a wide range of public policy issues.

Back home, Clinton holds a significant delegate lead against Sanders, but the senator has vowed to stay in the campaign until the party's July convention. His message calling for a political revolution to address wealth inequality and the influence of Wall Street on U.S. politics has galvanized many Democrats and independents.

Despite being enmeshed in an increasingly bitter campaign against Clinton, Sanders aides said the trip was not aimed at appealing to Catholic voters who comprise a large share of the Democratic electorate in New York and an upcoming contest in Pennsylvania.

The Vatican has been loath to get involved in electoral campaigns and usually tries to avoid any perception of partisanship involving the pope. Popes rarely travel to countries during the thick of political campaigns, knowing a papal photo opportunity with a sitting head of state could be exploited for political ends.

As a result, the invitation to Sanders to address the Vatican conference raised eyebrows and allegations that the senator lobbied for the invitation.

The chancellor for the pontifical academy, Bishop Marcelo Sanchez Sorondo, has said he invited Sanders because he was the only U.S. presidential candidate who showed deep interest in the teachings of Francis.

Other attendees included Morales of Bolivia and President Rafael Correa of Ecuador, along with Cardinal Oscar Rodriguez Maradiaga of Honduras, a member of the academy, and Columbia University professor Jeffrey Sachs, an adviser to the United Nations on environmental and sustainability issues. Sachs has advised Sanders on foreign policy issues.

The Rev. Matt Malone, editor of the Jesuit magazine America, said Sanders' trip was unlikely to have much of an impact on Catholic voters, noting that conferences like the one Sanders is attending "happen all the time."

"I don't think that Bernie Sanders going to the Vatican is going to help Bernie with Catholics any more than Ted Cruz going to a matzo factory is going to help him with the Jewish vote," said Malone, who served as a speechwriter to former Rep. Marty Meehan, a Massachusetts Democrat.

Popes rarely attend such events and do so only if the topic is of special interest and there is room in their schedule, Malone said.