A conservative super-PAC is attacking Republican presidential front-runner Donald TrumpDonald John TrumpZuckerberg launches public defense of Facebook as attacks mount Trump leaning toward keeping a couple hundred troops in eastern Syria: report Warren says making Israel aid conditional on settlement building is 'on the table' 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.