The speech was moved due to the threat of "extreme weather".
"Clearly team Obama felt that the risks of having this thing drenched in a thunderstorm outweighed the benefits that they got in Denver for a big outdoor crowd, and Clint Eastwood showed them last week what happens when a nomination acceptance speech gets undercut by circumstance," notes CNBC chief Washington correspondent John Harwood.
Republicans charged Democrats just couldn't fill the stadium.
"I think it also has more to do with attendance rather than precipitation," charged North Carolina Congressman Patrick McHenry.
Organizers say they had a waiting list of thousands.
With the stadium event canceled thousands who waited in line for seats are out of luck for Thursday.
"I was so excited. I got my tickets. I waited four hours in line for it, to just be denied," said Valerie LaCoille.
Democrats who had stadium tickets but won't be able to get inside Time Warner Arena Thursday night did get some good news from convention organizers in the form of a promise to try to get them tickets to see President Obama at some other place soon.