Tweet: Cant wait to give a big hug to my bestie @realDonaldTrump at the debate tomorrow night. I know you miss me !
Whitman, CEO of Hewlett Packard Enterprise, backed Republican New Jersey Gov. Chris Christie's presidential bid last year before switching her allegiance to Clinton in the general election.
Clinton has highlighted her support from business leaders like Cuban, Whitman and Warren Buffett on the campaign trail as Trump touts his own business success. But her association with them has opened her to criticism from both sides of the aisle that she is too friendly with the wealthy.