Preachers "ought to put their toe right on the line," said Mathew D. Staver, founder of Liberty Counsel, a nonprofit law firm that supports conservative Christian causes.

The Rev. Rick Scarborough, a leading evangelical in Texas, has recruited 5,000 "patriot pastors" nationwide to promote an agenda that aligns neatly with Republican platforms. "We urge them to avoid legal entanglement, but there are times in a pastor's life when he needs to take a biblical stand," Scarborough said. "Our higher calling is to Christ."

The campaign encourages individual pastors to use sermons, Bible studies and rallies to drive Christians to the polls -- and, by implication or outright endorsement, to Republican candidates. One online guide to discussing the election in church, produced by the Focus on the Family ministry, offers this tip: If a congregant says her top concerns are healthcare and national security, suggest that Jesus would make abortion and gay marriage priorities.

At a recent rally in Pennsylvania, Focus on the Family founder James C. Dobson told a crowd of 3,000 that it would be "downright frightening" if Republicans lost control of Congress. If there's a good Christian on the ballot, he said, failing to vote "would be a sin."

The law restricting political activity of churches and charities dates to 1954, when then-Sen. Lyndon B. Johnson pushed it through in a pique of anger over a nonprofit's effort to derail his reelection. Tax-exempt organizations, including churches, may not participate or intervene in political campaigns on behalf of any candidate. Intervention is broadly defined as "any and all activities that favor or oppose one or more candidate for public office," according to the Internal Revenue Service.

That sounds straightforward. In practice, though, there are many ways around the restriction, as the faithful recognize.

"If the pastor is doing the right job, the people will automatically vote for the right person," said Gale Wollenberg, who belongs to a conservative evangelical church in Topeka, Kan.

Perhaps the biggest loophole is that churches can campaign on policy issues -- even if that effort benefits a particular candidate. Scarborough, for instance, has spent a great deal of time far from his Texas parish, rallying Christian voters against an initiative promoting embryonic stem-cell research in Missouri. At his events, Scarborough makes a point not to mention Missouri's Republican Sen. Jim Talent, who is in a tight fight for reelection.

But in private, he says candidly that he expects -- and hopes -- his efforts will give Talent a boost. "If a pro-life candidate benefits from Christians being involved, to God be the glory," Scarborough said.

Pastors can further help their favored candidates by distributing "issue-oriented" voter guides in church, a tactic used for years among secular (often left-leaning) groups such as the National Assn. for the Advancement of Colored People and adapted to faith communities by the Christian Coalition in the 1990s.

The voter pamphlets are supposed to be neutral, but often present issues through a distinctly partisan lens. A guide distributed by a conservative group in Minnesota in 2004 laid out the candidates' views on aborting "unborn babies." One produced this year by the liberal evangelical group Sojourners describes immediate withdrawal of U.S. troops as the only way to bring peace to Iraq.

Pastors have a right to work directly for candidates on their own time, as long as they don't use church resources. In a recent article aimed at evangelical preachers, Staver wrote that they "should feel free" to go even further and endorse a candidate from the pulpit because he thought the IRS law was unconstitutional. He repeatedly noted that the IRS had rarely sanctioned churches. The Church at Pierce Creek in Binghamton, N.Y., is the only one ever to lose its tax-exempt certification, for sponsoring newspaper ads that opposed presidential candidate Bill Clinton.

Far more often, IRS agents resolve complaints by training church leaders to avoid future missteps, said Lois G. Lerner, who directs the IRS unit for tax-exempt groups. In 2004, the IRS resolved dozens of complaints this way, including such blatant violations as churches donating to a candidate's campaign or placing political signs on their property.

Given the slim chance of serious sanction, "I encourage pastors to exchange their muzzles for megaphones," Staver wrote in the Rev. Jerry Falwell's monthly newspaper, the National Liberty Journal.

Political preaching has been particularly fervent this season in Ohio, where two conservative mega-churches have promoted the Republican candidate for governor, J. Kenneth Blackwell. They've featured him in at least six rallies that blended patriotic appeals with Christian revival.

Yet the latest poll shows Blackwell trailing by 19 points. In part, that's because Ohio voters seem to be in an anti-Republican mood, after scandals involving state GOP politicians. It also shows that a pastor's influence only goes so far.

Many on the Christian right credit their aggressive mobilization, similar to this fall's campaign, with securing President Bush's reelection. And turnout among evangelical voters did jump 9% from 2000 to 2004.

But two religious groups that heavily back Democrats also came out in droves: Turnout was up 15% among Jews and 13% among mainline Protestants who attend liberal churches, according to surveys conducted by John C. Green, a senior fellow at the Pew Forum on Religion & Public Life. Overall turnout was up 4 points.

"It's really difficult to parse out" the effectiveness of the religious right's mobilization in 2004 "because it was such an intense campaign," Green said. "It does seem to bear fruit, but it varies a great deal from congregation to congregation."

Church-based campaigning may have been most influential in voters' choice of candidate. Bush won 78% of the evangelical vote in 2004, up from 68% in his first presidential bid. And evangelicals were far more likely than any other group of voters to say that religion was the most important factor in their political thinking.

Voter education from the church "can be enormously effective," said Colin Hanna, who directs the Pennsylvania Pastors Network. The group of 850 seeks to mobilize voters against "abortion and other evils," according to its website.

Some of this fall's efforts are aimed at energizing politically active but disillusioned Republicans who might otherwise stay home. But Hanna is particularly eager to reach the 30 million regular churchgoers, and an overlapping group of 19 million evangelicals, who did not vote in 2004. Their indifference to politics is "either a tragedy or a scandal," he said, but he's certain it can be overcome.

Liberals, too, see potential in mingling faith and politics. Black churches have a long history of political activism from the pulpit, dating to the civil rights movement -- but their efforts did not boost voter turnout in 2004. This time around, other Christians, including liberal Catholics, are jumping in to try to energize the religious left.

They plan to distribute more than 1 million voter guides urging Christians to evaluate candidates based on issues such as poverty and global warming. A new consulting firm, Common Good Strategies, aims to help Democratic candidates make stronger pitches to communities of faith.

For the most part, however, the left is far behind the right: "They've got organization and discipline that we don't really have yet," said Jack Pannell of Sojourners. "It may take us a generation."

With both the left and the right pursuing faith-based strategies, the IRS issued a warning in February that churches may be in danger of becoming "arms of political campaigns and parties." Agents are looking into about 40 reported violations by churches and other tax-exempt nonprofits. A few are holdovers from 2004, including the high-profile probe into an antiwar sermon at a liberal Pasadena church. But new allegations continue to come in at a brisk clip.

Liberal clergy in Ohio have filed a protest about the pastors' efforts on behalf of Blackwell. On the right, the website http://www.ratoutachurch.org is recruiting volunteers to report partisan activity from the pulpit that favors Democrats.

Melissa Rogers, a visiting professor of religion and public policy at Wake Forest University in Winston-Salem, N.C., says she expects more complaints as the election approaches. In their zeal to bring politics into the pews, some religious leaders "have made a decision to walk on the razor's edge of the law," she said. "Or over the edge."