what is the meaning of the expression:

"everything is up for the grabs"?

(from an article in the new yorker about Donald Trump campaign):

http://www.newyorker.com/news/daily-comment/obama-and-trump-after-dallas?mbid=nl_160709_Daily&CNDID=39597722&spMailingID=9177228&spUserID=MTE1NzQzMjk5MDE3S0&spJobID=960696633&spReportId=OTYwNjk2NjMzS0

thanks for your help.

luc.