WASHINGTON - The Rev. Mark Scott has become an overnight sensation. People jump out of cabs to meet him. They practically tackle him on the street. They show up at his Dorchester church in droves. And they ring him up at the rate of 100 calls a day.
''It's a deluge; it's out of control,'' said Scott.
He owes his sudden popularity to his role as outreach coordinator in the new White House Office of Faith-Based and Community Initiatives, not his old posts as director of the Ella J. Baker House or associate pastor of the Azusa Christian Community.
By pledging last month to make churches, synagogues, and mosques the government's partners in aiding the poor and needy, President Bush whetted the appetites of faith-based groups for a piece of the federal social-welfare pie.
He also stoked a vigorous debate about the initiative and his own commitment to the constitutional separation of church and state.
''I understand full well that some of the most compassionate missions of help and aid come out of faith-based programs,'' Bush said at a news conference yesterday. ''I strongly support the faith-based initiative that we're proposing, because I don't believe it violates the line between the separation of church and state, and I believe it's going to make America a better place.''
The primary mission of the White House office is to promote what Bush calls ''the armies of compassion,'' social ministries and community groups working to reduce poverty, and to improve their access to federal grants. The president also ordered similar offices set up in five Cabinet departments.
''We don't have a big pot of money,'' Scott said of the office, which opened Tuesday. ''This is a government-reform effort to level the playing field for faith-based and community-based groups.''
But even those who believe charities should play a larger role in meeting social needs question how the president's program will work. ''The devil is in the details,'' said Ronald Thiemann, a professor of religion and society at Harvard Divinity School.
Among the questions: Should federal grants be available to all faith-based groups, including controversial ones such as the Church of Scientology or the Nation of Islam? How will government agencies ensure that money meant for social services won't be spent on religious activities and that clients won't be proselytized? Can government agencies distinguish sham groups from legitimate social ministries without showing favoritism? And can religious groups accept government oversight and stay true to their missions?
Pat Robertson, founder of the Christian Coalition, predicted on his ''700 Club'' broadcast Wednesday that Bush's plan would face ''a real problem'' if it allowed religious groups such as the Hare Krishnas and the Unification Church to compete for federal grants.
''This thing could be a real Pandora's box,'' Robertson said. ''What seems to be a great initiative can rise up and bite the organizations, as well as the federal government.''
That is a ''serious and substantial issue,'' agreed Stephen Goldsmith, the former Indianapolis mayor who has helped shape Bush's program. But he added that many groups, including the Hare Krishnas, have created nonprofit spinoffs that already have won federal grants.
''Now these organizations may be a little less subtle in how they apply for money, but the test isn't whether they are faith-based - that would be awful - it is whether they can prove they are effective in delivering services,'' Goldsmith said.
Bush has also said he wants more resources for faith-based groups, but until he unveils his budget next week there is no blueprint for how the administration plans to pay for new social-service grants earmarked for them or how much seed money he will request for a proposed Compassion Capital Fund to get new social ministries running.
''Show me the money,'' said Sharon Daly, vice president for social policy at Catholic Charities. ''Show me how without it, community and faith-based groups are going to meet the needs of low-income people for housing and day care. If you take the current amount of money, which is already woefully inadequate, and spread it around in a different configuration, it is not clear what you have accomplished.''
Catholic Charities, the social-welfare agency of the Roman Catholic Church, already receives millions of government dollars each year to aid the poor.
Bush has proposed expanding the ''charitable choice'' provision of the 1996 welfare-overhaul law, which allows ministries that incorporate religious content to compete for federal funds to run mentoring, tutoring, job-training, and drug-rehabilitation programs.
Representative Robert C. Scott, a Virginia Democrat and a graduate of Boston College Law School, argues that charitable choice warrants congressional and judicial review. He contends the provision violates the US Constitution by allowing public funds to flow to groups that proselytize and to the ministries of some religions, but not others.
Despite such criticisms, Bush's plan has not run into much opposition on Capitol Hill. In part, that's because the only piece of his legislative plan filed to date is a package of tax changes to encourage charitable giving.
Many Democrats see the overall plan as an opportunity to argue for increased social spending. Senator Joseph I. Lieberman, a Connecticut Democrat, is expected to cosponsor Bush's initiative in the Senate.
Opposition is coalescing outside Congress. The Coalition Against Religious Discrimination, which includes civil-rights and liberal interfaith groups, intends to block Congress from expanding charitable choice. Richard Foltin, legislative director of the American Jewish Committee, said Bush ''may have done a favor'' by exposing the obscure provision to scrutiny.
''Our concern is that government money and power are not used through charitable choice to interfere with the religious liberty of minorities in our society,'' Foltin said.