The choice might come most easily for Sen. Hillary Clinton, D-N.Y., a presidential contender who has made the decision once before: when her husband occupied the Oval Office.

She and President Clinton were a regular presence at Foundry United Methodist Church, where during trying times in the White House she said she "drew great sustenance from the sermons and personal support" from its congregation and minister. Though the former president is a Baptist, Sen. Clinton and her daughter, Chelsea, are Methodists.

Growing up in Illinois, Hillary Clinton has said her involvement in the First United Methodist Church in Park Ridge "opened my eyes and heart to the needs of others and helped instill a sense of social responsibility rooted in my faith." She attended Bible school, Sunday school and a youth group there, she wrote in her book "Living History."

Clinton's challenger for the Democratic nomination, Sen. Barack Obama of Illinois, attends Trinity United Church of Christ, which has about 8,500 members in Chicago. Its Web site touts the church as "unashamedly black and unapologetically Christian," and devotes itself to addressing injustice.

Obama, a Christian, says his parents didn't practice religion (but he has had to battle persistent rumors that he is Muslim because he lived for four years with his stepfather in Muslim Indonesia).

Obama said in his book, "The Audacity of Hope," that he was drawn to "the power of the African American religious tradition to spur social change."

He said that when he realized that faith didn't mean relinquishing doubts, that gave him devotional strength.

"It was because of these newfound understandings -- that religious commitment did not require me to suspend critical thinking, disengage from the battle for economic and social justice or otherwise retreat from the world that I knew and loved -- that I was finally able to walk down the aisle of Trinity United Church of Christ one day and be baptized," he said.

Largely reserved about his personal beliefs, Sen. John McCain, R-Ariz., has said that his Episcopalian father prayed on his knees twice a day, and his own faith got him through the torture of being a prisoner of war in Vietnam.

Once, after an interrogation, he found scratched into a cell's walls, "I believe in God, the Father Almighty."

"There, standing witness to God's presence in a remote, concealed place, recalled to my faith by a stronger, better man, I felt God's love and care more vividly than I would have felt if had I been safe among a pious congregation in the most magnificent cathedral," he wrote in "Faith of My Fathers."

The presumptive Republican nominee told McClatchy Newspapers in June that he still refers to himself as an Episcopalian, but he began attending North Phoenix Baptist, where his wife, Cindy, and two of their children were baptized. He said he worships there because he found "the message and fundamental nature more fulfilling than I did in the Episcopal church. ... They're great believers in redemption, and so am I."

Former Arkansas Gov. Mike Huckabee, a Southern Baptist minister who is seeking the GOP nomination, attends services at the evangelical Church at Rock Creek in Little Rock.

Huckabee told the Christian Science Monitor last year that he liked that the church, at the time meeting in a storefront, was ministering to drug addicts and others trying to rebuild their lives.

"This is a church that was created for the people that no one else wants," he said.

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