Since the days of John F. Kennedy, modern politicians have tried to have it both ways on matters of religion, espousing personal religious beliefs that at times are at odds with their public policy pronouncements.
Democrat John Kerry is the latest candidate to navigate this terrain, offering himself as a practicing and believing Roman Catholic who nonetheless holds positions contrary to the teachings of his church. Mr. Kerry supports abortion rights, stem cell research, the death penalty for terrorists, and civil unions for gay couples, all opposed by the church hierarchy.
President Bush, to a much lesser extent, occasionally has found himself at odds with leaders of his denomination, as when prominent Methodist leaders preached against the war in Iraq as a violation of God's law.
Candidates who disagree with their church leaders aren't necessarily always in disagreement with their fellow parishioners, also known as voters.
American Catholics, for example, disagree with their church on birth control and a number of other issues, "and they're not going to punish Catholic politicians for sharing their views," said Alan Wolfe, a Boston College political scientist and the author of several books tracking social and religious trends.
"American Catholic politicians pay very little attention to the idea that their votes as public servants should be guided by their religion, and most American Catholics completely support that," Mr. Wolfe said.
In Mr. Kerry's case, his religion is "creating an affinity for him among Catholics," despite his disagreements with church teachings, said Democratic pollster Celinda Lake.
Recent polls show a majority of American Catholics support abortion rights.
The clash between a candidate's personal religious beliefs and public policy stances is getting a closer look this year in part because of increasing impatience among some Catholic leaders with politicians who claim the faith but say they don't want to legislate personal beliefs. Earlier this year, for example, Archbishop Raymond L. Burke, of St. Louis, said he would deny communion to Mr. Kerry because of his views. Archbishop Sean P. O'Malley of Boston, Mr. Kerry's hometown, suggested a similar penalty for those in conflict with the church without naming the senator.
The nation's Catholic bishops late last year created a task force to consider whether to recommend sanctions against Catholic politicians who favor policies contrary to church teachings. Among the options are denying access to Catholic schools or hospitals that might be used for campaign events to denying communion and seeking excommunication.
The task force is headed by Cardinal Theodore McCarrick, the Washington archbishop.
Mr. Kerry met privately with Cardinal McCarrick on April 15 for 45 minutes in what was characterized as a get-to-know-you session. It was not known whether the work of the task force came up.
Cardinal McCarrick declined comment on the meeting. But a few days earlier, he seemed open to some sort of sanctions, if not ready to go so far as to deny communion.
"I think there are many of us who would feel that there are certain restrictions that we might put on people, that there are certain sanctions that we may put on people," he recently told Fox News Sunday. "But I think many of us would not like to use the Eucharist as part of the sanctions."
Catholic conservative Deal Hudson, the editor of Crisis magazine, said that for religiously active voters, Catholic or otherwise, the key question is whether candidates are sincere rather than any specific matter of policy.
"Most religiously active people, and certainly most Catholics, have been convinced that Bush is very sincere about his religious convictions, even if they disagree with him," Mr. Hudson said. "People have yet to be convinced that Kerry is as sincere."
Mr. Bush frequently invokes religion in his public remarks and draws strong support from conservative Christians.
Mr. Kerry doesn't usually address religion directly but often casts his policy decisions in terms of moral imperatives rooted in faith. Asked about his policy differences with the church, Mr. Kerry has said, "I'm not running to be a Catholic president. I'm running to be a president who happens to be Catholic."
Mr. Kerry's base of support includes nonreligious voters, and he also is supported by a majority of nonconservative religious voters, in addition to nonwhite evangelicals and Catholics, according to a new bipartisan Battleground 2004 poll.
The significance of religion in this year's campaign is still a matter of debate.
Mr. Wolfe predicted that with so much focus on Iraq and the Sept. 11 terrorist attacks, the election is unlikely to turn on cultural issues. But Mr. Hudson said that in a close race, the importance of religiously active voters cannot be underestimated. He pointed to exit polls showing that Mr. Bush drew support from 47 percent of Catholic voters in the razor-tight 2000 election, up 10 percentage points from Republican Bob Dole's showing four years earlier.
Ms. Lake, the Democratic pollster, said Mr. Bush has seen some slippage in support among Catholics, which she said could be particularly important in Midwest battleground states that are heavily Catholic, such as Wisconsin and Missouri.