He will reportedly tell the DNC that "he is generating excitement and that's what the party needs."
"Who wants the endorsement of a guy ... who lost in perhaps the greatest upset in the history of Congress?"
"He has a lot of experience at being wrong," Rubio said of Biden, who is weighing a bid.
The former House majority leader will co-chair Bush's Virginia campaign.
The event underscores the strengthening ties between the two Republicans.
Clinton's campaign will coordinate fundraising with the national party.
Tom Perkins is now calling his vote to oust Fiorina "a mistake."
Jordan Fabian 08/27/15 03:24 PM EDT
The resolution to honor the vice president's son comes as Joe Biden weighs a 2016 bid.
Trump said the Univision anchor was "ranting and raving" during a press conference.
Biden is making a two-day visit to Florida as he weighs a run for president.