Trump, by way of Jimmy Kimmel, asked Sanders if he would launch a third-party bid.
Sanders scoffed at Clinton saying she's sure she'll be the party nominee.
Stirrings of a Trump-Sanders debate is putting the wheels in motion for an unprecedented showdown spectacle.
Trump is joining other Republicans in encouraging Rubio to run for reelection.
Martin Shkreli said he supports Trump over Clinton.
The ad uses the new State Department report about Clinton's private email server.
Sanders now has 43 superdelegates supporting him.
Fox News talked with members of Donald Trump's family in a Thursday special.
Sen. Boxer said Sanders has connected with young voters.
Trump said he would focus on states like New York and California that are usually a lost cause for Republicans.