Democratic lawmakers called for an investigation amid reports that a charitable foundation created by Zinke and run by his wife, Lola, was allowing a company co-owned by Halliburton chairman David Lesar to use the foundation’s land for a commercial development.

Zinke also met Lesar, Lesar’s son and Montana developer Casey Malmquist in his Washington, D.C., office last August, according to emails the Democrats received in a public records request.

“On June 20th, the OIG opened an investigative complaint into purported business activities by the Secretary,” inspector general spokeswoman Nancy DiPaolo said. “A preliminary review is underway.”

That review will determine whether the office opens a full investigation into the deal, though no timeline has been set, she said.

Interior spokeswoman Heather Swift said Zinke has done nothing wrong and that he resigned from his charitable foundation’s board of directors before the land deal was made.

“The Secretary adheres to all applicable laws, rules and regulations,” Swift said. “He goes above and beyond mere technical compliance and strives for full transparency. We are confident the IG report will confirm that.”

Democrats led by Rep. Raul Grijalva of Arizona, along with conservation groups, say it’s inappropriate for Zinke to be involved with a private land deal with a man whose company would benefit from the Trump administration’s push to increase energy drilling on public lands.

Halliburton spokeswoman Emily Mir has said Lesar’s commercial development in Whitefish has nothing to do with Halliburton, nor did Lesar’s meeting with Zinke in August.

In that meeting, Lesar was seeking background information about the land owned by Great Northern Veterans Peace Park Foundation that Zinke founded, Zinke said on the Voices of Montana radio program Wednesday.

Lesar is looking to build a hotel, microbrewery, art gallery and office space on land next to the park, which BNSF Railway donated to Zinke’s foundation in 2008. An agreement between Lesar’s company and the foundation now run by Lola Zinke gives Lesar’s company foundation land for a parking lot and another entrance to the property.

The Whitefish City Council approved a zoning change for the project in January, though Lesar’s company has not yet applied for permits to build.

This isn’t the first time Zinke has had to defend himself against accusations of improperly helping a company in his hometown. In October, Zinke denied influencing a $300 million contract awarded to a tiny company called Whitefish Energy Holdings to restore power to hurricane-damaged Puerto Rico.

Zinke knows the company’s CEO and his son once had a summer job with the company, but Zinke adamantly denied having anything to do with the Puerto Rico contract.