The Trump Organization will now begin widely using a long-available government resource to prevent staffing its properties with undocumented immigrants after media reports that the business had hired — and then fired — undocumented workers at its Trump-branded golf courses.

The organization, once headed by President Donald Trump and now managed by his sons Eric Trump and Donald Trump Jr., pledged to use the voluntary E-Verify system across all of its company locations on Tuesday. The government-run system allows employers to check employee-provided documents against federal records to ensure workers are in the country legally and authorized to work.

“We are instituting E-Verify on all of our properties as soon as possible,” Eric Trump, the company’s executive vice president, told several media outlets in a statement Tuesday. “We’re starting with the golf properties, and we are going to be doing all of them.”

The move comes as President Trump digs in his heels on illegal immigration after catalyzing a 35-day partial government shutdown, the longest in history. On Friday, he agreed to temporarily reopen the government for three weeks while lawmakers work out a permanent solution on border security and has since threatened to shut down the government again if he doesn’t get $5.7 billion for a wall on the U.S.-Mexico border.

During his 2016 presidential campaign, Trump said that he used E-Verify across his businesses. “I’m using E-Verify on just about every job,” he told MSNBC host Chris Matthews. While the Trump Organization has used E-Verify at some of its hotel and golf course locations, eight golf courses weren’t enrolled in the voluntary system, according to the Washington Post.

For years, the Trump Organization employed several undocumented immigrants at its flagship Trump National Golf Club in Bedminster, New Jersey, according to a New York Times report in December. Management was aware that the undocumented immigrants — who had been employed for years as housekeepers, landscapers, and kitchen staff — had used fraudulent documents at the time of their hiring, the Times reported. One worker from Guatemala even received help from a manager in securing her forged documents.

Weeks after the report, about a dozen workers were fired from the New Jersey club, according to the Times.

A dozen more undocumented, Latin American workers were suddenly fired from the Trump National Golf Club in Westchester County, New York earlier this month, according to the Washington Post. One employee told the Washington Post they had been with the company for nearly 15 years. Eric Trump told the Post that the Trump Organization often uses a third-party vendor called HireRight for its background checks.

On Tuesday, Democrats began gathering signatures to demand a probe into whether the president’s companies broke the law by hiring undocumented workers. And some former undocumented Trump Organization workers have met with Democratic Sens. Cory Booker and Robert Menendez to ask for protection from deportation, according to CNN.