Donald Trump’s pick to head the Internal Revenue Service pressed the agency to investigate and consider stripping the country’s leading animal welfare group of its tax status after it supported an initiative to protect dogs, according to documents reviewed by us.

If former Missouri Republican representative Billy Long is confirmed to run the Internal Revenue Service (IRS), he would be in a position to strip the tax status of such nonprofit groups whose missions he disagrees with — and effectively shut them down. And Long could have new powers to do so if Congress enacts a pending House-passed bill to grant the Trump administration new powers to rescind the tax status of groups it deems “terrorist supporting organizations.”

In 2011, Long signed a letter pushing the IRS to launch a probe of the tax-exempt status of the Humane Society of the United States, a nonprofit that focuses on animal welfare and opposes animal cruelty. The letter followed the Humane Society’s support of a successful Missouri ballot measure strengthening regulations on dog breeders.

The letter, which was signed by Long and five other members of Congress, claimed that public documents showed “beyond question that lobbying is a ‘substantial part’ of [the Human Society’s] activities, and feel the IRS’s failure to act is attributable to the politically sensitive nature of [the society’s] activities,” they argued. “Due to this, we write to request investigations by the Inspector General into [the Human Society’s] apparent improper activities and its tax-exempt status.”

The letter was then promoted by HumaneWatch, which is a project of the Center for Consumer Freedom — a tax-exempt nonprofit whose website says it “is supported by restaurants [and] food companies.” The center was founded by lawyer and corporate lobbyist Rick Berman.

According to the signees, the Humane Society donated money to influence legislation and employees “spend substantial time and effort advocating specific legislation, particularly by urging the public to contact members of legislative bodies.” They specifically point to the Missouri Dog Breeding Regulation, which requires large-scale dog breeding operations to provide each dog with sufficient food, clean water, housing, and space, along with necessary veterinary care, regular exercise, and adequate rest in between breeding cycles. The ballot measure passed in 2010.

Long’s letter was subsequently cited by the Center for Consumer Freedom in its efforts to undermine the Humane Society’s participation in animal welfare policy in Connecticut.

Long also signed a separate letter in 2015 demanding the IRS investigate the tax status of the Clinton Foundation.