St. Peter's Square during the Easter Mass given by Pope Francis on April 5, 2015. (Franco Origlia/Getty Images)

Gerald Posner’s book “God’s Bankers: A History of Money and Power at the Vatican” was published in February.

Pope Francis begins his much-anticipated visit to the United States this week with popularity ratings that are the envy of every U.S. politician. He also arrives with a well-deserved reputation as a reformer. During his more than two years as pope, he has supercharged a wide-ranging overhaul of the scandal-plagued Institute for the Works of Religion, or the Vatican Bank. Since its World War II creation, the bank had often served as an offshore haven for tax evaders and money launderers and frustrated six of Francis’s predecessors. Little wonder that public figures of all faiths are clamoring to share the spotlight with this pope. From a meeting with the president to an unprecedented address to a joint session of Congress, plenty of politicians hope to bask in the “Francis effect.”

Francis’s visit will be a missed opportunity, however, if America’s leaders and many presidential aspirants don’t push to resolve a long-standing impasse between the United States and the Vatican over the church’s steadfast refusal to open all its Holocaust-era archives.

Those sealed records may help settle debate about whether the wartime pope, Pius XII, could have done more to prevent the Holocaust. They could also resolve questions about the extent to which the Vatican did business with the Third Reich, particularly whether it invested in German and Italian insurance companies that earned outsize profits by escheating the life insurance policies of Jews sent to the death camps.

Although Francis is a progressive pope, he is unlikely to act unless U.S. leaders forcefully push the issue of historical transparency. I know this firsthand, since my own numerous appeals to the Vatican for access to the archives, including a personal one to Pope Francis, have gone unanswered.

The American-Vatican dispute on this issue started in 1996, when Bill Clinton was president and John Paul II was pope. That summer, World Jewish Congress President Edgar Bronfman Jr. sat next to Hillary Clinton at a Democratic National Committee fundraiser. Bronfman asked the first lady for a meeting with the president to discuss a fresh campaign for recovering Nazi-looted Jewish assets. When Bronfman met the president the following day, he convinced him the United States should lead a renewed restitution drive. Clinton ordered 11 U.S. agencies to review and release all Holocaust-era files and urged other countries and private organizations with relevant documents to do the same.

The Vatican refused.

Initially, it declined to join 25 nations in collecting documents across Europe to create a comprehensive guide for historians. At a 1997 conference on looted Nazi gold in London, the Vatican was the only one of 42 countries that rebuffed all requests for archival access. At a 1998 restitution summit in Washington, it ignored an emotional plea by U.S. Secretary of State Madeleine Albright and stood aside as 44 countries approved an ambitious plan to return Nazi-looted art and property, settle unpaid life insurance claims and reaffirm the call for open access to Holocaust-era archives.

Subsequent pleas for opening the files by Bill Clinton, the State Department and Jewish organizations went unanswered. Enthusiasm over a 1999 Vatican announcement to allow Jewish historians into the wartime archives was short-lived. Access was limited to 5,000 documents that had been selected and published years earlier by four handpicked Jesuit academics.

After 2000, pressure to open the church’s files subsided. Historians were swamped with millions of newly declassified documents from more than a dozen countries and many restitution claims morphed into complex class-action lawsuits. During the last years of John Paul II’s papacy and the eight years of Benedict XVI, only a handful of Jewish advocacy groups pressed the issue.

That is why the 2013 papal election of Buenos Aires’s cardinal Jorge Mario Bergoglio seemed so promising. Bergoglio had a reputation for good relations with Argentina’s Jewish community. In 2010, he co-authored a book of conversations about faith with Abraham Skorka, an Argentine rabbi and friend. When Skorka had asked about the Holocaust files, Bergoglio was unequivocal: “What you said about opening the archives relating to the Shoah seems perfect to me. They should open them and clarify everything. The objective has to be the truth.”

In January 2014, after meeting with Francis, Skorka raised expectations by saying that the release was imminent. Observers familiar with the Vatican’s arcane, unwritten archival rules knew the church traditionally released the files of a pope 75 years after the start of a papacy. March 2, 2014, marked that date for Pius XII. It seemed a way for Francis to satisfy reformers who wanted the files released while claiming to traditionalists he was simply following precedent.

But March 2 came and went. Attention shifted to Francis’s May trip to the Holy Land. Some Vaticanologists predicted Francis would use the dramatic backdrop of Yad Vashem, Israel’s national Holocaust Memorial, to announce the policy change. But the trip passed without Francis even mentioning the files. Waldo Wolff, vice president of Argentina’s leading Jewish organization, added a sense of urgency to the Jerusalem visit: “If the Vatican’s archives are to be opened, it should be sooner rather than later, because time is running out for those to whom it would matter most.”

On the only occasion when the Pope has subsequently addressed the Holocaust — in impromptu remarks to young Catholics in June — it was only to castigate the “great powers” for not bombing “the railway routes that the trains took to Auschwitz.”

While he has avoided the controversy over Pius XII’s silence, Francis has demonstrated he is fundamentally different than his wartime predecessor. This month he urged “every parish, every religious community, every monastery, every sanctuary of Europe” to accept some of the Muslim refugees fleeing the fighting in Syria and Iraq. Such a directive by Pius XII might have saved tens of thousands of Jewish lives during World War II.

If Francis does not act to open the Vatican’s Holocaust-era files, they could stay sealed for a very long time. It took more than 400 years for the church to release some of its Inquisition files. And it was not until 2007 — after more than 700 years — that the Vatican cleared the Knights Templar of a heresy charge and opened the trial records.

Will any U.S. public official or presidential candidate take up the cause of Holocaust victims and ask Pope Francis to publicly commit to a time frame by which the Vatican will at long last open its secret World War II archives? In the autocratic world of Vatican governance, all that is needed is a papal decree.