Was wondering about the photo overlooking the Bellagio fountains. Then I discovered that POTUS was supposed to hold a fundraising dinner for Heller after the rally at an undisclosed location. Guessing it was held at the Bellagio. Photo and Tweet could have originated there during the dinner - or maybe POTUS is staying the night in the Presidential Suite? Interesting.
P.S. Cost was $50K per couple and that would also get them a photo op with the President.