Editor's Note: Since this story was published, Barack Obama tapped his Senate colleague, Joe Biden of Delaware, to be his running mate on the Democratic ticket. For more on how Biden, a Catholic, impacts the 2008 race, click here.

Michael Sean Winters has a name for Democrats who have abandoned their party in recent years: Catholics.

In Left at the Altar: How the Democrats Lost the Catholics and How the Catholics Can Save the Democrats, Winters, a columnist for the Catholic World, argues that the Democrats discovered how to win presidential elections only when, in the 1930s, they formed a left-center alli­ance with working-class Catholics. This lasted half a century, until Catholic voters deserted Jimmy Carter in 1980. The party would lose five of the next seven elections, and in 2004, Senator John Kerry would fail to carry the Catholic vote. If that does not sound astonishing, imagine Senator Barack Obama losing the black vote. “How did the Demo­crats lose the Catholics?” a bishop asked Winters. He attempts to answer this very question.

Long before pundits fretted about women or the African American vote, Catholics created the template for demo­graphic groups in American politics. The target of shameful bigotry, Catholics were reviled by erstwhile liberals beginning with Tom Paine. In time, with their growing numbers, Catholics grabbed control of city halls (as would other groups), but the ultimate power in Washington remained off-limits. Even when John F. Kennedy secured his party’s nomination for president, the influential Calvinist preacher Norman Vincent Peale felt no shame in warning, “Our American culture is at stake.”

Kennedy rejected any religious influence on his politics; as Winters notes, he “was interested in bringing Catholics into the mainstream even if it meant leaving Catholicism itself at the door.” Not so dissimilarly, Obama’s appeal is partly that of a black man who does not wear his ethnicity on his sleeve.

What interests Winters, though, is not that Catholics opened the door for ethnic and religious groups, but the way in which their moral and cultural values helped inspire a successful Democratic coalition. He begins his story with Monsignor John Ryan, an early-20th-century priest who championed social causes like unemployment insurance. A founder of the National Council of Christians and Jews, Ryan became a confidant of such New Dealers as Frances Perkins and Felix Frankfurter. During Franklin D. Roosevelt’s first campaign for president, Ryan served as an informal adviser, and he gave the benediction at F.D.R.’s second inauguration. In naming this chapter “The Priest and the President Create the New Deal,” Winters rather comically overstates Ryan’s role; he presents no evidence that Ryan influenced Roosevelt, only that Ryan was in sync with F.D.R.’s agenda.

Yet is Winters right in arguing that the New Deal had a Catholic flavor? I think he is. The Democratic agenda of the ’30s was tied to the notion of community. Its vision was more social than economic; hence it offered support for artists, public-works programs, and farm communities. It championed labor unions, which had as profound a role in knitting together neighborhoods as did the Roman Catholic Church. The soul of the New Deal was aimed, parish­like, at neighborhood and town.