President Trump on Thursday signed an executive order relaxing the enforcement of rules barring religious entities from participating in politics.

Marking the National Day of Prayer at the White House Rose Garden on Thursday, Trump signed the controversial order that weakens enforcement of an IRS rule that bars tax-exempt groups from endorsing political candidates. It instructs the IRS to use "maximum enforcement discretion" over the regulation, known as the Johnson Amendment, that applies to nonprofit organizations and churches.

"We are giving churches their voices back," Trump said at the signing.

The order also seeks regulatory relief for religious objectors to an Obama administration mandate requiring contraceptive services as part of health plans.

Trump brought up members of Little Sisters of the Poor, an order of Catholic nuns involved in a case against the mandate brought before the Supreme Court, before signing the order at the White House on Thursday.

"I want you to know that your long ordeal will soon be over," he told them.

TheStreet Recommends

Trump on the campaign trail promised to "totally destroy" the Johnson Amendment, a regulation named for then-Senator Lyndon Johnson. Put in place in 1954, it prohibits partisan political activity for tax-exempt organizations, such as churches, and bars outright political endorsements from the pulpit. According to the Associated Press, the rule has rarely been enforced.

Thursday's executive order is not as harsh as a draft leaked in February that could have allowed federal contractors to discriminate against LGBT employees or single mothers on the basis of faith, the Washington Post notes.

Washington, D.C. watchdog group the Campaign Legal Center warned that Trump's order could open elections to taxpayer-subsidized dark money.

"Rolling back enforcement of limitations on partisan activity by religious institutions could offer wealthy donors a way to not only influence elections anonymously, but also get a charitable tax deduction for doing so," said Brendan Fischer, federal and FEC reform program director at the Campaign Legal Center. "Religious leaders are already allowed to discuss political matters; they are just not able to use tax-deductible resources to engage in partisan electoral activity."

The ACLU has threatened to sue over the order.

Editors' pick: Originally published May 4.