Windows blogger Paul Thurrott and The Verge website are both reporting the new, later date for the announcement, originally intended for April.
The announcement event will likely be a small one, The Verge reported, offering the first details of the console code-named Durango; Microsoft reportedly will unveil the actual product at the E3 event in Los Angeles in June, with the console hitting shelves later in the year, CNET reported.
Rumors of a higher price -- $500 -- and a requirement for an "always on" Internet connection to play games have been making the rounds, CNET said, although Microsoft had declined to comment.
"We do not comment on rumors or speculation," Microsoft spokesman said in a statement provided to CNET. "We are always thinking about what is next for our platform, but we don't have anything further to share at this time."