NEW YORK — The images were vivid: President Donald Trump brandishing a Bible outside an Episcopal church in Washington that had been boarded up amid racial injustice protests. Episcopal leaders reacted with outrage at what they deemed a cynical photo-op.

“He didn’t say a prayer. … It was used as a matter of partisan politics,” said Michael Curry, the denomination’s presiding bishop.

That flare-up was notable for another reason. It’s one of the few times that a mainline Protestant denomination entered the national spotlight amid a volatile election year abounding in political news about evangelicals and Catholics.

There’s been a steady stream of news about certain evangelical leaders — their close alliance with Trump, their occasional defiance of coronavirus-related restrictions on worship services. Meanwhile, Trump’s Democratic rival, Joe Biden, is being assailed by some fellow Catholics, including bishops, for his support of pro-choice policies.

Rarely garnering national attention are the mainline Protestant denominations that dominated America’s political and civic leadership for much of its history, beginning in colonial times.

These denominations, including the Episcopal, United Methodist and Presbyterian (U.S.A.) churches, are now deeply engaged in campaigns against racism and voter suppression. Yet they haven’t generated controversies this year as headline-grabbing as those involving evangelicals and Catholics.

“Mainline Christians are often quieter in their public rhetoric,” said Florida-based Bishop Kenneth Carter, former president of the United Methodists’ Council of Bishops.

“But my experience has been, in every city I’ve lived … that many mainline Christians do the heavy social lifting in their communities on issues such as homelessness and food insecurity.”

Carter noted that the United Methodists, the largest mainline denomination with about 7 million U.S. members, is politically diverse. Its members include Democrat Hillary Clinton, former presidential candidate, senator and secretary of state, and conservative Republican Jeff Sessions, a former senator and U.S. attorney general.

“In every mainline church, you’ll find members who are Republican and Democrat,” said the Rev. John Dorhauer, president and general minister of the 800,000-member United Church of Christ.

“What that means is that the pastor and church culture have created a setting where, no matter what your political view is, you’re free to worship here,” he said. “When a pastor crosses the line, you risk saying to a member of a church, ‘Your own beliefs are not valued here.’”

In general, mainline denominations discourage their pastors from making political endorsements from the pulpit, or from issuing voter guides the way some conservative churches do.

“We don’t endorse or oppose a particular candidate, but we do try to uphold moral principles and values that are key to our faith,” said Curry.

Through the mid-20th century, most Protestants in the U.S. belonged to mainline churches, but now they are outnumbered by evangelicals. Polls in recent years indicate that about one-quarter of U.S. adults identify as evangelical, and less than 15% as mainline Protestant. The collective membership of the seven biggest mainline denominations is now about 16 million.

The mainline churches have been politically active in a number of less-partisan ways, notably in registering voters and recruiting poll watchers. In many cases, they also have aligned with the widespread protests against racial injustice and police violence against Black people.

The Presbyterian Church (U.S.A.) launched a Rally for Justice march Aug. 28 from its headquarters in Louisville, Kentucky, the city where Breonna Taylor was fatally shot by police during a raid on her home in March. The Evangelical Lutheran Church in America — the second-largest mainline denomination with 3.5 million members — sponsored a prayer service in Kenosha, Wisconsin, on Sept. 2 in response to outrage over the wounding of Jacob Blake by an officer who fired seven shots into his back.

At that service, Paul Erickson, bishop of the ELCA’s Greater Milwaukee Synod, denounced racism as “that toxic poison that is harming us all.”

Elizabeth Eaton, the presiding bishop of the ELCA, said whites make up 94% of the denomination — the biggest share among the major mainline denominations — and hopes it can prove its commitment to racial justice after periods in the past “where we did not engage.”

Among the relatively small number of mainline clergy with national prominence is a Disciples of Christ pastor from North Carolina, the Rev. William Barber, a long-time Black civil rights activist and leader of the Poor People’s Campaign who has been outspoken against systemic racism.

Three mainline denominations now have Black leaders holding the top clerical post — exemplifying a broader commitment in mainline communities to diversity and racial justice.

Curry became the Episcopalians’ first Black presiding bishop in 2015; the Presbyterian Church (U.S.A.) elected the Rev. Dr. J. Herbert Nelson II in 2016 as the first Black leader in its more than 300-year history; and the Rev. Terri Hord Owens became the first Black woman to head any of these denominations when she was elected the Disciples of Christ’s president in 2017.

“We’re seeing the emergence of leaders who not long ago wouldn’t have been heard from,” said Nelson.

Most mainline denominations have seen membership drop sharply in recent decades. The number of Presbyterians, for example, has fallen from about 2.5 million in 2000 to some 1.3 million today.

Some defections have come as several of the denominations moved to ordain LGBT clergy and recognize same-sex marriages, and the United Methodist Church faces a seemingly inevitable schism next year over those same issues.

Another challenge for the mainline churches is one confronting many other faiths: Persuading young people to participate.

“Young people want to be engaged with people who are doing stuff,” Owens said. “It’s not just what kind of music you play. It’s what are you doing to change and shape society.”

“We all recognize the declining numbers,” Owens added. “We have to be visible doing the work of justice. It’s hard work for all of us.”