As part of Pulpit Freedom Sunday, religious leaders across the country will endorse political candidates — an act that flies in the face of Internal Revenue Service rules about what tax-exempt organizations, such as churches, can and cannot do.

The IRS says tax-exempt organizations, or what they refer to as a 501(c)(3), are prohibited from participating in partisan campaigning for or against political candidates. Yet, despite what's in the rules, the agency continues to struggle to do anything about those who defy the law.

Though the regulation has been in place since 1954, in 2009, a U.S. District Court in Minnesota ruled the IRS no longer had the appropriate staff to investigate places of worship after a reorganization changed who in the agency had the authority to launch investigations.

New procedures for conducting church audits have been pending since 2009, which has left the IRS virtually impotent in conducting any kind of new investigations. The IRS did not respond to questions.

Despite the lack of manpower, organizations such as Alliance Defending Freedom, a Christian legal ministry that first launched Pulpit Freedom Sunday in 2008, say they take the IRS restriction seriously — even as they disagree with it.

"Every pastor and every church has the right to decide what their pastor preaches from the pulpit and to not have that dictated to them by the IRS," said Erik Stanley, senior legal counsel for the Arizona-based Alliance Defending Freedom, formerly the Alliance Defense Fund.