Billionaire presidential candidate Donald Trump is suing over where he slept during a recent Las Vegas campaign stop.

Trump's companies that own the Trump International Hotel in Las Vegas with fellow billionaire Phil Ruffin filed a federal lawsuit against the Culinary Workers Union and Bartenders Union on Oct. 14 accusing the groups of saying he stayed overnight at Ruffin's unionized Treasure Island casino-resort instead of his own Trump Hotel.

The Culinary Union has been pushing to unionize Trump's hotel.

The trademark lawsuit says the unions distributed a flyer stating that "when Donald Trump stays in Las Vegas, he stays at a union hotel."

Not so, say Trump's lawyers who say the Republican presidential candidate stayed at the Trump hotel Oct. 7 and Oct. 8 before speaking inside the Treasure Island.