Thirty-three Republican members of the Colorado legislature joined last year with the Alliance Defending Freedom (ADF), a national anti-choice and anti-LGBT organization, in demanding the Colorado health department investigate Planned Parenthood, according to a letter released by ADF via Colorado State Sen. Kevin Lundberg’s office.

Considered to be one of the most powerful Christian right organizations in America, ADF is well-known at the Colorado legislature for pushing legislation and testifying in favor of the social-conservative agenda.

But it’s rare to see ADF form a direct alliance with so many legislators, as it did in advocating for a Planned Parenthood investigation.

“I’m not surprised to see ADF branching out into working alongside state legislators,” said Robert Boston, author of Taking Liberties: Why Religious Freedom Doesn’t Give You The Right To Tell Other People What To Do, via an email. “While I’m not aware of efforts on this scale in other states, I do know that ADF has of late been sending unsolicited ‘advice’ to state and local lawmakers concerning issues like the ability of government clerks to refuse service to same-sex couples. The influx of Tea Party-style Republicans in state governments since 2014 has given the group a host of natural allies in the state capitols, and it’s not surprising to see this relationship growing.”

While its work directly with legislators isn’t widely seen, ADF has a longstanding and multi-pronged history of attacking Planned Parenthood, including efforts to defund the health-care organization and to organize grassroots opposition among people and businesses. The organization’s anti-choice and anti-LGBTQ stances are widely documented.

In a 2015 handbook designed to help religious entities discriminate without facing legal repercussions, ADF equates bestiality and incest with being LGBTQ, participating in adultery, and using pornography.

“We believe that God wonderfully and immutably creates each person as male or female,” states the handbook. “These two distinct, complementary genders together reflect the image and nature of God. (Gen 1:26-27.) Rejection of one’s biological sex is a rejection of the image of God within that person.”

The handbook continues: “We believe that God intends sexual intimacy to occur only between a man and a woman who are married to each other. (1 Cor 6:18; 7:2-5; Heb 13:4.) We believe that God has commanded that no intimate sexual activity be engaged in outside of a marriage between a man and a woman. We believe that any form of sexual immorality (including adultery, fornication, homosexual behavior, bisexual conduct, bestiality, incest, and use of pornography) is sinful and offensive to God. (Matt 15:18-20; 1 Cor 6:9-10.)”

ADF, which did not return a call for comment, campaigned in support of a 2003 Texas lawsuit, arguing that it’s “clearly” true that “same-sex sodomy is a distinct public health problem.” ADF has backed efforts to criminalize homosexuality abroad, according to a report by Media Mattes for America.

ADF has gained attention more recently for providing legal defense for anti-LGBTQ business owners who refuse to serve same-sex patrons.

“ADF and its allies are attempting to reverse something like 50 years of social progress,” wrote Boston, who serves as communications director for Americans United for Separation of Church and State, a national progressive organization. “They are essentially at war with modernity. Some might argue that this is alarmist, and it won’t happen. But the fact is, reproductive rights have been under constant assault since Roe v. Wade was decided in 1973, and opponents of legal abortion have made a lot of progress.”

In the September 25 letter to the Colorado Department of Public Health and Environment (CDPHE), GOP lawmakers requested the “standards or criteria that are required to initiate an investigation” of Planned Parenthood, and it asked how a heavily edited video that falsely purported to show illegal dealings in fetal tissue donation would not be investigated.

The video and others like it, part of an undercover series by the anti-choice front group the Center for Medical Progress (CMP), has been discredited and their creators indicted, but the videos have spawned local and national Republican-led hearings and investigations of Planned Parenthood. No evidence has shown Planned Parenthood to have broken any laws.

The ADF letter, which has not been previously reported on, came after CDPHE, in an August 31 letter, rejected a demand by many of the same state legislators to “initiate an investigation” of Planned Parenthood.

Among the GOP lawmakers listed on ADF’s letter calling for an investigation of Planned Parenthood are State Sen. Laura Woods (R-Westminster), whose fate in November’s election, some say, could determine whether Republicans maintain control of the Colorado Senate, and State Sen. Tim Neville (R-Littleton), who was rejected by Republicans to run against Democratic U.S. Senator Michael Bennet this fall.

State Rep. JoAnn Windholz (R-Commerce City), who’s been asked to resign after blaming Planned Parenthood for being the “true instigator” of November’s deadly shooting at a Planned Parenthood clinic in Colorado Springs, was also listed as a signer.

Multiple calls for comment on the letter and ADF’s legislative priorities were made to Rep. Dan Nordberg (R-Colorado Springs), whose name appears first among the lawmakers listed on the letter, were not returned.

Many of the Colorado legislators aligned with ADF were part of an unofficial “hearing” in November focused largely on the CMP smear videos, that turned into a day-long condemnation of Planned Parenthood. It took place just over two weeks before three people were murdered at the Colorado Springs Planned Parenthood clinic, which re-opened fully Sunday.

The ADF letter, which was included in an ADF briefing book distributed to legislators at the “hearing,” also requested public documents from CDPHE, including all correspondence with Planned Parenthood, pursuant to Colorado’s open records law.

It was signed by senior ADF Counsel Michael J. Norton, who left ADF in December to start the Colorado Freedom Institute, which will focus on conservative religious causes.

Norton, who drafted a 2006 amendment that voters added to the Colorado Constitution defining marriage as between a man and a woman, testified frequently at the state capitol and has been an outspoken advocate for anti-choice campaigns.

Norton did not return emails asking if the lawmakers who joined his former organization’s letter support ADF’s broader agenda of criminalizing homosexuality and defunding Planned Parenthood.