(OPINION) The U.S. presidency is a geezer’s game this round.

If Donald Trump wins and completes a full term he'd be 78, while a President Joe Biden would be 82 – thus the unusually intense buzz about Sen. Kamala Harris as president in waiting. Either man would be history’s oldest president.

On the religion beat, Pope Francis appears spry but he turns 84 in December and, inevitably, writers are already starting to muse about his successor. An election campaign for the leader of 1.3 billion Catholics is the religion writer’s equivalent of the Olympics, compounded by secrecy and subtlety. This should be an unusually hot race because Francis has roiled conservatives on both doctrinal and political matters.

Francis’s dozens of appointees to the College of Cardinals will exercise major voting power in the coming “conclave,” but that doesn’t mean his successor will be a clone. Cardinals chosen by the doctrinaire St. John Paul II and Benedict XVI, after all, elected Francis. (As religion specialists will know, only cardinals under age 80 are electors and their total cannot exceed 120, with a two-thirds majority required to win.)

Further on the age factor. Some will say the rule of thumb has moved to older popes, as with the U.S. presidency, since both Francis and predecessor Benedict XVI were in their later 70s when chosen. However, back in 1958 the cardinals elevated a similarly aged Angelo Roncalli, the patriarch of Venice. Some figured he’d be a mere caretaker; in fact, he summoned the epochal Second Vatican Council.

One final age factor. It seems inconceivable that the cardinals would choose a youngster like Pope Pius IX, who was only 54 when elevated and had a turbulent 32-year reign.

By odd coincidence, two conservative Catholic publishers have simultaneously issued relevant pre-conclave books with the identical title, though the subtitles signal different purposes.

Journalists will certainly want keep on hand Sophia Institute Press’s “The Next Pope: The Leading Cardinal Candidates” by Edward Pentin, Vatican correspondent for the National Catholic Register. (To reach Pentin or obtain a review copy, contact publicist Sarah Lemieux at 603-641-9344).

A blurb by Raymond Arroyo, EWTN cable’s news anchor and frequent Fox News gabber, proclaims Pentin “the pre-eminent Vatican reporter of his generation” (snubbing the legendary Victor Simpson of The Associated Press, among others. Who’s on your list?).

This book is not only an essential resource for journalists, since many cardinals lack media coverage, but will help the cardinals, who often know little about each other. Pentin profiles the priestly careers and religious views of the 19 cardinals considered papabile (“pope-able”), as the Italians say. It’s important to bone up on all the men in this elite group because those who aren’t finalists will influence other voters.

Note the review of Pentin by our colleague Clemente Lisi. Looking at conservative cardinals chosen by Benedict, Lisi highlights Raymond Burke (whom I discounts as a candidate. Too scratchy and, worse yet, an American). Also, the leading personality from the robust church in Africa, Robert Sarah, 75, who heads the Holy See’s office on worship. The Italians include Angelo Scola, 78, retired archbishop of Milan, a major player in the last conclave.

The second book is Ignatius Press’s “The Next Pope: The Office of Peter and a Church in Mission” by George Weigel of the Ethics and Public Policy Center, well-known for his biography of John Paul II. Rather than a rundown on politics and candidates, Weigel promotes his preferred program for the next pontiff. He wants someone who will suppress the flexible “Catholic Lite” approach to church teaching, yet also a bold reformer who’ll somehow end the priestly molestation scandals and achieve the oft-promised cleanup of the Vatican bureaucracy, finances included. (Weigel’s office: 202–682–1200 or catholicstudies@eppc.org.)

This Memo allows me, who participated in three of these white-smoke marathons, to send valentines. At Time magazine, Rome Bureau Chief Jordan Bonfante and colleagues identified Albino Luciani in 1978 as a top candidate and thus our cover had the only color portrait available to U.S. media. Then these virtuosos allowed Time alone to identify Karol Wojtyla as a prospect before his surprise election.

With Joseph Ratzinger’s elevation in 2005, I was on the AP team that included Simpson, talented U.S. partner Rachel Zoll and research director Lynn Dombek, a fellow Time Inc. refugee whose comprehensive data bank on every cardinal was available online for instant use by every bureau worldwide.

Richard Ostling is a former religion reporter for the Associated Press and former correspondent for TIME Magazine. This piece first appeared at Get Religion.