Several large coalitions are mobilizing religious communities nationwide in support of overhauling the nation's health-care system.

In recent weeks, hundreds of clergy members and lay leaders have descended on the offices of members of Congress, urging lawmakers to enact health-care legislation this year. With face-to-face lobbying, sermons, prayer and advertising on Christian radio stations, the coalitions are pressing the idea that health care for everyone is a fundamental moral issue.

But organizing groups with disparate religious beliefs around a single goal has been challenging. The coalitions have had to tiptoe around sensitive issues, such as whether to support a government-run health insurance option and whether government-subsidized plans should pay for abortions. They have also had to deal with some clergy members' fears of offending their congregations by speaking out for universal health care.

"It's a pretty radical step for this congregation to get involved in the public arena," said the Rev. Jennifer Thomas, who is pastor of Immanuel Lutheran Church, a largely middle-class congregation in Kansas City, Mo., and is also a leader in one collection of grass-roots community and national religious groups. "A few members wonder how much the church should be involved."

The efforts have been coordinated closely with the Obama administration. A group of faith leaders met with President Obama in April, and administration officials took part last month in a rally at Freedom Plaza with representatives of more than 40 denominations and faith groups in support of comprehensive health coverage.

Showing up at the rally were Joshua DuBois, executive director of the White House Office of Faith-Based and Neighborhood Partnerships, and Neera Tanden, senior adviser to the Department of Health and Human Services.

"Your united voice is critical," Tanden told the gathering. "We are, in the next two months, at the most critical time of trying to get [health-care] legislation passed."