The tax bill proposed by House Republicans on Thursday includes a proposal to modify the Johnson Amendment, the 63-year-old law prohibiting politicking by churches that has been a favorite target of conservative Christian groups and of President Donald Trump.

The Republicans’ bill would make it legal for ministers and other religious leaders to endorse candidates from the pulpit but stops short of allowing other political participation such as financial contributions from churches to campaigns.

The bill stipulates that a religious institution wouldn’t be found to have violated the law “solely because of the content of any homily, sermon, teaching, dialectic, or other presentation made during religious services or gatherings.”

That’s the protection that some religious leaders, mainly conservative Christians, have requested for years in the name of “pulpit freedom,” even though the IRS has almost never penalized clergy for the content of a sermon.

“It’s really a carve-out to make sure, in the views of those who support it, that the pulpit is a free-speech zone, if you will,” said Charles Haynes, an expert on religious liberty at the Newseum.

Trump often touted his opposition to the Johnson Amendment when speaking to evangelical pastors during his presidential campaign, and at the National Prayer Breakfast soon after his inauguration, he said he would “totally destroy” the 1954 provision. He issued an executive order in May, surrounded by religious leaders he invited to the Rose Garden, in which he directed the IRS not to penalize clergy for political speech.

What House Republicans propose in their tax bill would not “totally destroy” the Johnson Amendment. First, their proposal specifically applies only to religious institutions, not to all tax-exempt nonprofit organizations, which are restricted from supporting political candidates under the law. Haynes said that treating religious groups differently in this way appears to be legal; the other groups “don’t have free exercise of religion to be protected.”

Second, the tax bill’s language would lift only the ban on endorsing a candidate during a speech, such as a sermon or church teaching. It would not free churches up entirely to participate in the political process — a prospect that many observers had feared when Trump spoke about eliminating the code.

Without the Johnson Amendment, donors could give their money to churches, which could then give it to political candidates — making political donations effectively tax-exempt and bypassing the laws on campaign donation disclosures.

“That would really change the system in a way that I think would cause tremendous conflict and confusion in the political arena,” Haynes said. “That’s what President Trump keeps saying, ‘We’re going to get rid of the Johnson Amendment.’ I would think, ‘Gee, does he mean that?’ And apparently he doesn’t.”

But even the narrow amendment that Republicans want to make to the law drew criticism Thursday from religious and nonreligious groups.

The Rev. Barry Lynn, executive director of Americans United for Separation of Church and State, said in an email, “The House GOP leadership and President Trump want to turn America’s houses of worship into centers of partisan politics. It’s a reckless scheme that may please Trump’s allies in the religious right, but could spark a blowback since the vast majority of Americans, faith leaders and houses of worship are firmly opposed to it. This is a bad idea that should be immediately dropped.”

Larry T. Decker, executive director of the Secular Coalition for America, called the proposal in a statement “a brazen attack on the separation of church and state.” And the Baptist Joint Committee for Religious Liberty argued in a statement that inviting politics into the sanctuary is bad for churches, saying the House proposal “threatens to destroy our congregations from within over disagreements on partisan campaigns. . . . This change has been pushed by a tiny minority and is opposed by the vast majority of Americans and churchgoers, across party lines and faith traditions.”

In February, the month that Trump highlighted his opposition to the Johnson Amendment at the National Prayer Breakfast, 89 percent of evangelical pastors told the National Association of Evangelicals that they do not think clergy should endorse politicians from the pulpit. Churchgoers tend to agree; in a Lifeway poll, 79 percent said they would not want their pastor endorsing a candidate in a sermon.

Conservative Christian groups that have advocated for a repeal of the Johnson Amendment were not as quick to issue statements about the lawmakers’ proposal Thursday.

At Becket, a law firm focused on religious liberty that represents clients opposed to the Johnson Amendment, attorney Daniel Blomberg praised the Republican proposal. “We think it’s about time that Congress got involved and corrected the IRS’ unconstitutional overreach here,” he said.

Blomberg said his firm doesn’t have a position on whether the bill should have gone further, protecting not just speech but financial involvement in a campaign. Speech has generally been the focus of pastors who fear they might be violating the Johnson Amendment, he said: “They solve that problem, they solve 98 percent of the problem.”