A northern Minnesota preacher's presidential endorsement from the pulpit of Republican John McCain over the weekend is part of a national challenge of federal restrictions on such political expressions.

The Rev. Gus Booth of Warroad Community Church made his endorsement Sunday as part of the Alliance Defense Fund's "Pulpit Freedom Sunday." The fund said Booth and other pastors around the country were exercising "their First Amendment right to preach on the subject, despite federal tax regulations that prohibit intervening or participating in a political campaign."

Booth, a delegate to the Republican National Convention in St. Paul, said Monday he did not set out to break a law but to challenge conflicting laws.

"The scripture is very clear about our need to obey all laws," he said. "I want people to realize that there are two laws here that compete with each other. The IRS says that I cannot talk about politics. The Constitution says I can. Unless there's a court battle, we don't know which law to obey."

Booth said he is aware his church could lose its tax-exempt status, "but it's not that big a deal. ... The church will go on."

He said his congregants have supported him, but he added that he's likely done sermonizing about presidential candidates. "I said what I had to say, and everyone knows how I feel about it," he said. "Now it's time to move on to something else."

Americans United for Separation of Church and State on Monday filed complaints with the IRS over six churches whose pastors endorsed candidates from the pulpit on Sunday.

"These pastors flagrantly violated the law and now must deal with the consequences," said Barry Lynn, executive director of Americans United. "This is one of the most appalling religious right gambits I've ever seen. Church leaders are supposed to tend to Americans' spiritual needs, not behave like partisan political hacks. I urge the IRS to act swiftly in these cases."

Americans United cited what was said at each church. Booth said: "We need to vote for the most righteous of candidates. And it doesn't take a brain surgeon to figure that out. The most righteous is John McCain."

The IRS said in a statement it is aware of Sunday's initiative and "will monitor the situation and take action as appropriate." The IRS forbids churches "from directly or indirectly participating or intervening in any political campaign on behalf of, or in opposition to, any candidate for public office."

The Alliance Defense Fund's mission is "to protect and preserve religious liberty, the sanctity of life, marriage and the family."

"Pastors have a right to speak about biblical truths from the pulpit without fear of punishment," said Erik Stanley, the fund's senior legal counsel. "No one should be able to use the government to intimidate pastors into giving up their constitutional rights. If you have a concern about pastors speaking about electoral candidates from the pulpit, ask yourself this: Should the church decide that question, or should the IRS?"

In June, Booth alerted Americans United that he was challenging the prohibition on political advocacy from the pulpit. He gave a sermon in May warning followers to oppose Barack Obama for his stance on abortion rights.

In response, Americans United asked the IRS to investigate whether the evangelical church with a following of 150 was violating its nonprofit, tax-exempt status.

A U.S. appellate court upheld the revocation of tax-exempt status of a New York church that took out a newspaper ad urging Christians to vote against Bill Clinton in the 1992 presidential election.

Star Tribune staff writer Jeff Strickler contributed to this report. Paul Walsh • 612-673-4482