The Vatican under the first American Pope is rolling out a new campaign to urge ordinary Catholics to help bail out the deficit-ridden Holy See.
Leo celebrated Mass in St Peter's Basilica, marking the Feast of Saints Peter and Paul and thanked donors who have contributed, using the language of the publicity campaign to say their financial support was a sign of union with his young pontificate.Â
In churches around the world, Masses on the July 29 feast day often include a special collection for Peter's Pence, a fund which both underwrites the operations of the central government of the Catholic Church and pays for the Pope's personal acts of charity.
The church is using a promotional video, poster, QR code and website soliciting donations via credit card, PayPal, bank transfer and post office transfer.
The Vatican is betting that an American-style fundraising pitch under the Chicago-born Leo will do more to help keep the Holy See bureaucracy afloat and erase its 50 million to 60 million euro ( $A87 million to $A104 million) structural deficit.
The video features footage of Leo's emotional first moments as Pope, when he stepped out onto the loggia of St Peter's Basilica and later choked up as he received the fisherman's ring of the papacy.
With an evocative soundtrack in the background, the video superimposes a message, available in several languages, urging donations to Leo via the Peter's Pence collection.
"With your donation to Peter's Pence, you support the steps of the Holy Father," it says.
"Help him proclaim the Gospel to the world and extend a hand to our brothers and sisters in need. Support the steps of Pope Leo XIV. Donate to Peter's Pence."
At the end of his noon blessing on Sunday, Leo used the same language about his first steps to say the Peter's Pence fund is "a sign of communion with the Pope and participation with his Apostolic Ministry."
"From the heart, I thank those who with their gifts are supporting my first steps as the successor of St Peter," he said.
The fund has been the source of scandal in recent years, amid revelations the Vatican's secretariat of state mismanaged its holdings through bad investments, incompetent management and waste.
The recent trial over the Vatican's bungled investment in a London property confirmed the vast majority of Peter's Pence contributions had funded the Holy See's budgetary shortfalls, not papal charity initiatives as many parishioners had been led to believe.
On top of the budget deficit, the Vatican is also facing a 1 billion euro (about $A1.78 billion) shortfall in its pension fund that Pope Francis, in the months before he died, warned was unable in the medium term to fulfil its obligations.
Unlike countries, the Holy See doesn't issue bonds or impose income tax on its residents to run its operations, relying instead on donations, investments and revenue generated by the Vatican Museums, and sales of stamps, coins, publications and other initiatives.
For years, the United States has been the greatest source of donations to Peter's Pence, with US Catholics contributing about a quarter of the total each year.
Vatican officials are hoping that under Leo's pontificate, with new financial controls in place and an American math major running the Holy See, donors will be reassured that their money won't be misspent or mismanaged.