After the furor over Marco Rubio's attendance last week, which ended with Rubio attending CPAC, Donald Trump has heightened the intrigue by bailing on the event, after promising to attend.
— CPAC (@CPAC) March 4, 2016
No clue at this point why Trump has decided to not attend. Trump has nothing on his Twitter feed and no official explanation has been put forth by the CPAC folks.
It's an interesting contrast with Rubio, who is clearly ill and more in need of time on the campaign trail, who has taken the time to attend.