Vegas Shooter Stephen Paddock Got Aggressive with Chicago Hotel Manager Before Lollapalooza

Stephen Paddock got a guaranteed room with a view that overlooked the Lollapalooza festival because he was aggressive and demanding with the hotel manager ... TMZ has learned.

TMZ broke the story ... Paddock booked 2 rooms at the Blackstone Hotel for early August that coincided with the music festival. He booked the rooms through Expedia, and requested rooms with a view of Grant Park, but he couldn't get a guarantee.

As we reported, Paddock then called the hotel and someone entered a note in the computer that his view room was guaranteed ... despite the fact that's against hotel policy.

Now we've learned how Paddock got the guarantee. He got a manager on the phone and was aggressive, saying he needed the view because he and his wife met at Lollapalooza years back and this was an anniversary trip. Our sources say Paddock was "forceful" on the phone, and it worked.

Our sources say the hotel's general manager is downloading law enforcement on the bookings and conversations.