A conservative super-PAC is attacking Republican presidential front-runner Donald TrumpDonald John TrumpHR McMaster says president's policy to withdraw troops from Afghanistan is 'unwise' Cast of 'Parks and Rec' reunite for virtual town hall to address Wisconsin voters Biden says Trump should step down over coronavirus response MORE for hiring undocumented workers.

"How much do we really know about Donald Trump?" the narrator asks in a TV ad released Friday.
 
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"A federal court ruled that Trump's company hired illegal immigrants to help the construction process for Trump Tower. He even paid a million dollar fine."
 
The ad also cites a Washington Post report that many of his construction workers had entered the country illegally.
 
"Trump makes big money off illegal immigrants," the narrator continues. "Can conservatives trust Donald Trump?"
 
The 30-second ad was created by Our Principles PAC, which is almost entirely funded by $3 million in contributions from Marlene Ricketts, part of the billionaire family that owns the Chicago Cubs.
 
Earler this week, Trump threatened the Ricketts family over Twitter over their campaign spending.