The protest, called Pulpit Freedom Sunday, was organized by the Alliance Defense Fund, a consortium of Christian lawyers that fights for conservative religious and social causes. When the fund first announced the protest this year, it said it planned to have 50 ministers taking part. As of Thursday it said it had hundreds of volunteers, but had selected only 33 who were fully aware of the risks and benefits.

The fund did not make the list of participants public, saying that it had received phone calls threatening to disrupt the sermons. One participant reached by telephone said he could not talk about it.

Another participant, the Rev. Luke Emrich of New Life Church, a small evangelical church in West Bend, Wis., demurred when asked which candidate he planned to endorse on Sunday.

“I would say endorsement is a strong word,” he said. “I’m planning to make a recommendation. I’m going to evaluate each candidate’s positions in light of Scripture and make a recommendation to my congregation as to which candidate aligns more so.”

The fund provides legal support for religious conservatives who have long felt aggrieved at what they say are limits on their religious expression.

Organizers said they wanted a range of clergy of various faiths and political persuasions to join the protest, but acknowledged that the participants might be “weighted” toward the conservative end of the spectrum and more likely to support the Republican candidate, Senator John McCain, than the Democrat, Senator Barack Obama.

Erik Stanley, senior legal counsel with the Alliance Defense Fund, said: “This is not something these churches want to do in secrecy and hiding. In fact, they don’t believe they’re doing anything wrong. They don’t believe they’re violating the law.