Early Wednesday morning, Donald Trump called Jerry Falwell Jr. and woke him up with news the Liberty University president has long been waiting to hear. The new Republican platform, the GOP nominee told Falwell, calls for the repeal of a half-century-old tax law prohibiting churches and tax-exempt institutions from political organizing.

“He was so excited,” Falwell says. “After 30 years of the so-called conservative leaders who have been elected by evangelicals, none of them thought to advocate for the repeal of the Johnson amendment, giving evangelical leaders political free speech. … He thinks it is going to be a revolution in the Christian world.”

The “Johnson Amendment,” as the 1954 law is often called, is a U.S. tax code rule preventing tax-exempt organizations, such as churches and educational institutions, from endorsing political candidates. At the time, then-Senator Lyndon B. Johnson was running for re-election, and he and other members of Congress pushed the amendment to stop support for their political opponents’ campaigns, George Washington University law professor Robert Tuttle has explained. Many have also argued the amendment served to stop black churches from organizing to support the civil rights movement.

“All section 501(c)(3) organizations are absolutely prohibited from directly or indirectly participating in, or intervening in, any political campaign on behalf of (or in opposition to) any candidate for elective public office,” the IRS explains of the rule on its website. “Violating this prohibition may result in denial or revocation of tax-exempt status and the imposition of certain excise taxes.”

Repealing the amendment was a priority of the Trump campaign in the GOP platform meetings this week in Cleveland. “They understand the importance of religious organizations and nonprofits, but religious organizations in particular which is what the Johnson Amendment affects, to have the ability to speak freely, and that they should not live in fear of the IRS,” said Tony Perkins, president of the Family Research Council, who is on the Republican platform committee. “That is a priority in the platform, and from the Trump folks, it is a priority of the campaign, and will be a priority of the administration.”

In recent years, religious liberty group the Alliance Defending Freedom has advocated for its repeal, arguing that the law is unconstitutional and lets the IRS “tell pastors what they can and cannot preach,” and “aims to censor your sermon.”

Falwell, an early Trump endorser, has long opposed the amendment. When he endorsed former Arkansas Gov. Mike Huckabee in the 2008 presidential race, Americans United for the Separation of Church and State complained to the IRS and called for an investigation of Liberty University. Falwell countered by documenting ways the law is used only to file complaints against conservative groups. “It intimidates the leaders of the organizations from exercising free speech,” Falwell says. “The law is a farce, it is not enforced, and it is time for it to go.”

Franklin Graham, son of American preacher Billy Graham, has also faced IRS investigations for his organizations Samaritan’s Purse and the Billy Graham Evangelistic Association. He wrote to President Obama in 2013 to complain. “I believe that someone in the Administration was targeting and attempting to intimidate us,” he wrote. “This is morally wrong and some would call it ‘un-American.’”

Rev. Barry W. Lynn, executive director of Americans United, responded to the shift in the GOP platform to TIME. “Changing current restrictions on church politicking will corrupt the church’s mission, violates the beliefs of many parishioners and creates another giant loophole in campaign finance,” he says.

Trump’s supporters hope the move further cements Trump’s support in the GOP’s most reliable voting-bock, white evangelicals. Nearly 80% of white evangelicals already support Trump, slightly more than supported Mitt Romney in 2012, according to a new report from the Pew Research Center, and they prefer Trump on nearly every issue, from “improving economic conditions” to “managing federal government.”

“This is something that could make a difference with Christian voters in the fall,” Falwell says. “It is almost as important for Christians as the appointment of Supreme Court justices.”

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