President Trump vowed Thursday to “totally destroy” a law passed more than 60 years ago that bans tax-exempt churches from supporting political candidates, a nod to the religious right that helped sweep him into office.

Speaking at the National Prayer Breakfast in Washington, Trump said he would seek to overturn the Johnson Amendment, which prohibits tax-exempt nonprofits — including churches and other houses of worship — from “directly or indirectly” participating in a political candidate’s campaign.

Repeal of the amendment — which is part of the tax code and would require action by Congress — has been sought primarily by conservative Christian leaders, who argue that it is used selectively to keep them for speaking out freely.

But several experts said Thursday that the effect of a repeal could be far broader, allowing churches of any political leaning to pour their financial resources into campaigns of like-minded candidates.

“It’s less about a minister speaking out from the pulpit, and more about deep church coffers,” said Beth Gazley, a professor of public affairs at Indiana University.

President Trump and Sen. John Boozman (R-Ark.), bow their heads in prayer during the National Prayer Breakfast in Washington on Thursday. (Win Mcnamee/Bloomberg News)

David Herzig, a Valparaiso University tax law professor, said repeal of the amendment has the potential to turn houses of worship “into super PACs.”

[What is the Johnson Amendment and why should people care?]

While prospects for congressional action remain uncertain, legislation consistent with Trump’s aims has already been introduced in both chambers of Congress.

House Speaker Paul D. Ryan (R-Wis.) suggested Thursday that he is open to repeal. “I’ve long believed that,” Ryan said when asked at a news conference about Trump’s call. “Yeah, I’ve always supported that.”

The amendment is named for Lyndon B. Johnson, who introduced it in the Senate in 1954, nine years before he became president.

During his remarks Thursday, Trump cast the issue as one of free speech and free exercise of religion.

“I will get rid of and totally destroy the Johnson Amendment and allow our representatives of faith to speak freely and without fear of retribution,” Trump said. “I will do that, remember.”

House Speaker Paul Ryan (R-Wis.) said Thursday he supports allowing tax-exempt churches to directly support political candidates, which is currently barred under federal law. (Alex Wong/Getty Images)

The renewed promise, which Trump first made as a candidate, was applauded by evangelical Christian leaders who endorsed his Republican presidential bid, including Jerry Falwell Jr., president of Liberty University.

“It’s a law that restricts free speech, and it never should have been passed in the first place,” Falwell said.

In reality, the Internal Revenue Service rarely punishes churches for political statements. For several years, more than 2,000 pastors have joined what they call “Pulpit Freedom Sunday” to test the ban by speaking their political views in their sermons. The IRS only investigated once and did not punish in that case, according to the conservative organization that organizes the annual effort.

Falwell argued, however, that the law remains a threat and that “it’s enforced selectively” by the IRS.

[Donald Trump gave a doozy of a speech at the National Prayer Breakfast]

Exit polls showed Trump defeating Democratic nominee Hillary Clinton 80 percent to 16 percent among white evangelical Christians.

A repeal of the Johnson Amendment, however, would affect not only conservative churches aligned more closely with Republicans but also open new avenues of support for liberal African American churches and others more in sync with Democrats.

Houses of worship make up just a fraction of the universe of so-called 501(c)(3) organizations in the United States, all of which are restricted by the Johnson Amendment. A range of other educational and charitable organizations also bear that designation, including the Clinton Foundation and the Donald J. Trump Foundation.

Under current law, churches are free to engage in political activity; the restrictions under the Johnson Amendment are triggered by their receipt of tax-exempt status.

Several legal experts, including Herzig, noted a potential downside to allowing churches to operate like political action committees: Because churches are not required to make the same disclosures as PACs, campaign funding funneled through churches could be less transparent.

“The repeal of the Johnson Amendment would unleash a new wave of dark money into the political system,” Larry T. Decker, president of the Secular Coalition for America, said in a statement.

Trump made no mention Thursday of when he might ask Congress to overturn the law or what restrictions would remain under such a proposal.

A spokesman for Rep. Steve Scalise (R-La.), the House majority whip and sponsor of the House version of the bill, said Trump’s support provides a boost for repeal efforts. Spokesman Chris Bond said Scalise will work with GOP lawmakers and the White House “to move the ball forward and protect free speech.”

Even short of congressional action, however, Trump has “tremendous power” to keep the IRS from enforcing the Johnson Amendment, Herzig said.

Lifeway, a Christian polling firm, found in 2015 that 79 percent of Americans thought pastors should not endorse candidates during worship services. Evangelicals were more likely to say pastors should be able to do so — 25 percent compared with 16 percent of all respondents — but support for clergy endorsements was low across the board.

Trump’s broadside against the Johnson Amendment has found eager supporters, though, including Falwell and other evangelicals who supported his campaign.

[During the campaign: Why so many evangelicals had faith in Donald Trump]

On the other hand, many religious groups say they like their nonpolitical status just fine the way it is. After Trump spoke Thursday morning, for example, the Baptist Joint Committee for Religious Liberty quickly issued a statement saying repealing the Johnson Amendment would not further the religious liberty that they stand for.

“Politicizing churches does them no favors,” the organization said. “The promised repeal is an attack on the integrity of both our charitable organizations and campaign finance system.”

Trump voiced his opposition to the Johnson Amendment during a speech in June to a group of hundreds of conservative Christian faith leaders who met with him in New York.

He also noted his opposition during his acceptance speech at the Republican National Convention in Cleveland, where the party made the repeal part of its platform.

During his speech, Trump also spoke about the importance of evangelicals, saying: “They have so much to contribute to our politics, yet our laws prevent you from speaking your minds from your own pulpits.”

On the Sunday before the election, Trump’s running mate, Mike Pence, was featured in a video played in evangelical churches, citing two reasons to support his ticket: the appointment of pro-life Supreme Court justices and the promise to repeal the Johnson Amendment.

Mary Anne Marsh, a Democratic consultant, said Trump’s reiteration of the latter pledge on Thursday was emblematic of the course he’s charted since taking office.

“It’s clear Trump has spent the first two weeks appealing to his base,” she said. “He’s doubled down on that rather than appealing to all Americans.”