Sen. Dan Patrick is releasing a new statewide ad touting his stance on border security, on the same day a Dallas Morning News article is raising questions over undocumented workers once employed at one of his sports bars.

A private investigator hired by Patrick’s opponent Jerry Patterson located 48-year-old Miguel Andrade. Andrade told the paper that he and three other undocumented workers from Mexico worked one of Patrick’s Houston-area sports bars in the 1980s. He told the paper that while Patrick did not hire him personally, he was aware he was living in the country illegally and that “Patrick wrote him a letter of recommendation to help him establish temporary residency after a 1986 federal law offered amnesty for undocumented immigrants.”

Patrick, who is one of four Republicans vying for lieutenant governor, has been outspoken about the need to end illegal immigration across the Mexico border. Other parts of his platform include doing away with sanctuary cities, ending in-state tuition for undocumented students and prohibiting employers from knowingly employing undocumented workers.

He denies knowledge of Andrade’s status and is accusing his opponents of playing dirty politics. “They found a former employee of ours, out of hundreds, who says a manager, not me, hired him around 1984 as a dishwasher,” he said in a Facebook post. “The worker admits when required to fill out W4 employment forms he supplied false documents & social security number.” Patrick says the worker is also lying about other allegations, including that he offered to help Andrade visit Mexico.

You can watch Patrick’s new ad, below.