Six decades after John F. Kennedy became the first Roman Catholic president, his political ascent still reverberates in the American electorate. Generations of Catholics who had long been marginalized in the political process were emboldened to seek office, prompting a wave of Catholic lawmakers in the decades that followed.

Academic observers attribute the rising influence of Catholics to a new prominence in public life that emerged after Kennedy’s election. The number of Catholics in Congress has risen by roughly 50 percent since the Kennedy administration and in recent years, Catholics have consistently been the single largest religious denomination in Congress.

Members of all Christian faiths — a wide swath that includes Baptists, Episcopalians, Mormons and those unaffiliated with a specific denomination — equate to at least 87 percent of Congress. But it is Catholics, the biggest Christian denomination, who will hold at least 29 percent of the seats in the 117th Congress and two of the most powerful offices in government. With President-elect Joe Biden and Speaker Nancy Pelosi both Catholic, there will be a power dynamic not seen since the early 1960s when Kennedy and John W. McCormack made history as the first Catholic president and speaker.

“It’s emblematic of this long-term trend of Catholics running for office, getting elected to office, staying in office and being politically successful to the point that you could have so many Catholics in positions of power in Congress,” said Matthew Green, who chairs the politics department at Catholic University of America.

Catholics also have a growing influence on committee gavels. Seven House committee chairs are Catholic, up one from the 116th Congress. The group includes leaders with wide jurisdictions: Rosa DeLauro on Appropriations, Richard E. Neal on Ways and Means, Frank Pallone Jr. on Energy and Commerce and Jim McGovern on Rules.

The rise of Catholics in Congress has even outpaced the number of followers of the faith in the nation. The Pew Research Center in 2019 found that only 20 percent of Americans identified as Catholic, compared to 29 percent of lawmakers on Capitol Hill.

“Congress often is a lagging indicator of the changing religious makeup of the country,” Green said. He noted that Catholics were historically underrepresented in the Congress until the later part of the mid-20th century.

Most Catholics — including large numbers of Irish, Italian and Polish immigrants — were kept in a “religious and urban ghetto” in the 19th century, according to Rev. Matt Malone, the editor-in-chief of the Jesuit magazine America.

But that changed after Kennedy’s election to the highest office in the nation. “They were now being educated, moving into the middle classes, they were going to college; it makes sense now that they were also running for Congress, in places where traditionally they hadn’t,” Malone said.

Religious makeup of the 117th Congress

While Catholics continue to dominate much of the rank and file in Congress, Protestant leaders will still be prominent in the 117th Congress: Senate GOP leader Mitch McConnell, House Minority Leader Kevin McCarthy and Vice President-elect Kamala Harris are all Baptists. And unspecified Protestants — Christians who do not identify with a specific denomination — make up the second-largest religious bloc behind Catholics at 20 percent.

Orthodox Christians, the smallest non-Protestant Christian denomination in Congress, will see their totals rise from five to seven, including incoming Indiana freshman Republican Victoria Spartz, a Ukrainian immigrant, and returning Rep. Darrell Issa, R-Calif., who is an Antiochian Orthodox Christian.

Jewish lawmaker totals will be largely unchanged — and will depend on the outcome of the Senate runoff elections in Georgia, where Jewish Democratic candidate Jon Ossoff is challenging Republican Sen. David Perdue, a Methodist. Still, there was a notable shift in where Jewish lawmakers were elected in 2020.

While New York’s Jewish senator, Charles E. Schumer, is returning as Senate Democratic leader, the state is losing half of its Jewish delegation, including influential House members such as Appropriations Chairwoman Nita M. Lowey, who is retiring. Foreign Affairs Chairman Eliot L. Engel was defeated in a primary by Jamaal Bowman, one of 20 lawmakers who identify as unspecified or nonreligious. In Massachusetts, Jake Auchincloss, who is Jewish, was elected to the seat being vacated by fellow Democrat Joseph P. Kennedy III, the grandnephew of the nation’s first Catholic president.

Like their Jewish counterparts, the demographics of Catholic lawmakers are also changing. The growth of Catholic lawmakers following the Kennedy administration drew from descendants of the European Catholic diaspora. But Hispanic lawmakers are increasingly coming into the fold to succeed white Catholic lawmakers. Hispanic Catholics, who will account for 31 of 40 Hispanic House members and four out of the five senators, are finding a place in Congress as a new group of Catholic lawmakers.

In the House, California’s Pete Aguilar will be the Democratic Caucus’ vice chairman, replacing outgoing Assistant Speaker Ben Ray Luján of New Mexico as the highest-ranking Hispanic Catholic in Democratic leadership. Luján is joining the Senate’s incoming freshman class.

From a policy standpoint, Catholics have one of the biggest tents in Congress. Catholic lawmakers range from being known for their strict stances against abortion like New Jersey Republican Christopher H. Smith, to progressives who cite their faith in social justice causes such as New York Democrat Alexandria Ocasio-Cortez. Experts say that given the broad worldview of Catholics, those in leadership positions may not always agree on policy positions, but there is a fundamental shared language of faith.

Biden and Pelosi have both invoked their faith in public life. Biden regularly attends mass and quoted the widely known Catholic hymn “On Eagle’s Wings” during his Nov. 7 victory speech. In a December 2019 news conference, Pelosi had a heated exchange with a reporter: “I don’t hate anybody,” she said. “I was raised in a Catholic house. We don’t hate anybody, not anybody in the world.”

The steady growth among Catholics in politics also speaks to how American Catholics view their faith as integral to public service, according to John Carr, Georgetown University’s director of the Initiative on Catholic Social Thought and Public Life. He points to a teaching from Pope Francis that “faithful citizenship is a moral obligation. … Catholic faith, Catholic culture, Catholic experience is about getting involved and trying to make things better.”

That’s a point New York Democratic Rep. Tom Suozzi has taken to heart. The co-chairman of the National Prayer Breakfast readily draws a parallel to his Catholic faith and politics. “The most fundamental concept of the Catholic religion is to find the common good, to serve the common good. That’s what politics really should be about, is to really serve the common good,” he said.

Ryan Kelly contributed to this report.