President Trump reportedly will sign an executive order Thursday intended to allow churches to engage in more political activity without losing their tax-exempt status.

Trump, who has long promised to undo the 1954 "Johnson Amendment" that prevents churches from directly endorsing political candidates or taking part in campaigns.

Although repealing the tax law would require an act of Congress, Trump's order may direct the IRS not to enforce the law against members of the clergy, the New York Times reported.

Earlier Thursday, Senate Democrats warned Republicans against revising the rules surrounding churches and charities, in reaction to the prospect that Trump and the congressional GOP may seek to repeal the Johnson Amendment through tax reform.

Undoing the Johnson Amendment "will effectively lead to the elimination of our nation's campaign finance laws," Sens. Ron Wyden of Oregon, Bill Nelson of Florida, and Bob Casey of Pennsylvania wrote in a letter sent to Republican leaders and heads of the relevant committees.

Allowing churches to become "shell companies" for political interests would force authentic churches and charities to compete with lobbies for charitable donations, they cautioned.

Trump earned some praise from evangelical supporters on the campaign trail for promising to end the Johnson Amendment, although many churches favor the restrictions. Rep. Kevin Brady, chairman of the House Ways and Means Committee, which is drafting tax reform legislation, has said that he supports including repeal in the broad tax code overhaul.

Under current law, organizations that have tax-exempt status, including churches, are prohibited from directly engaging in politics. In practice, the IRS does not investigate ministers for political statements. A greater concern, however, is that churches could begin engaging in political contributions.

The House Oversight Committee is scheduled to have a hearing on the Johnson Amendment Thursday.