Democratic presidential contender Bernie Sanders told a Vatican conference today that young people are no longer satisfied with an economy "of stark inequality and injustice" and want instead an economy that looks out for the common good.

Sanders said today's youth — in the United States and elsewhere — are looking for a "return to fairness" and an economy that ensures everyone has access to health care, nutrition and education.

"Our youth are no longer satisfied with corrupt and broken politics and an economy of stark inequality and injustice," he said.

Sanders was speaking at a Vatican conference commemorating the 25th anniversary of St. John Paul II's 1991 encyclical Centesimus Annus on the economy and social justice at the end of the Cold War.

He made the trip hours after Thursday night's Brooklyn debate with rival Hillary Clinton and said the opportunity to address the Vatican conference was too meaningful to pass up. The roughly 24-hour visit will precede a crucial New York primary against the former secretary of state on Tuesday.

A Sanders supporter holds a welcome sign at the Vatican. (Stefano Rellandini/Reuters)

Sanders said in an earlier interview with The Associated Press that he was "appreciative and proud" to be invited to the conference organized by the Pontifical Academy of Social Sciences.

"The theme from the conference, which is essentially how we create a moral economy, is one that has occupied my attention for decades. And the teachings from Pope Francis have moved me very much," the Vermont senator said.

Sanders, the first Jewish candidate to win a presidential primary, called the trip "an opportunity that comes once in a lifetime."

Pope a no-show

Pope Francis has apologized that he couldn't personally greet participants of a Vatican conference.

Bishop Marcello Sanchez Sorondo read aloud the hand-written note of apology from the Pope right before Sanders took the floor Friday.

In it, Francis said he had hoped to swing by the conference, located in a villa deep in the Vatican gardens, later Friday evening. But he said couldn't pull it off because he was busy preparing for his upcoming trip to Greece on Saturday.

Francis asked Sanchez to "greet the speakers and participants, requesting their understanding of this situation. I will keep them all in my prayers and good wishes, and send them my heartfelt thanks for their participation."

In the run-up to his brief Vatican visit, Sanders had said he would welcome a meeting with Francis.

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.

Catholic voters

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.

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. - Rev. Matt Malone,

Other attendees will include Presidents Evo Morales of Bolivia and 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.

Morales met for about a half-hour Friday morning with Francis before heading into the conference. Morales raised eyebrows with an unusual gift for the pontiff: three books about the health benefits of the coca leaf, the raw ingredient for cocaine.

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 Congressman Marty Meehan, a Massachusetts Democrat.