Sanders drew jeers from his own supporters when he urged his delegates to back Hillary Clinton.
The emails angered many supporters who were already dismayed by Clinton’s choice of Tim Kaine.
Republicans called on the administration to make public key documents in the Clinton email case.
Sandford’s trial is set to begin on 22 August, said US Attorney’s Office spokeswoman Natalie Collins.
Profile of Hillary Clinton
It is unclear what Democrats would do if Clinton were to be indicted and if any contingency plan exists.
Trump has said he wants a political veteran to help him navigate the power corridors of Washington.
The announcement came amid concerns from his backers that he does not have money to fund his campaign.
Trump has focused much of his energy in recent days on the mass shooting in Orlando.
Obama formally endorsed Hillary Clinton’s White House bid on Thursday & called for Democrats to unite.
Hillary Clinton reached the 2,383 delegates needed to become the presumptive Democratic nominee.
California is the final big contest in the long, bitter fight for the Democratic nomination.
Donald Trump says he expected to put 15 states in play in the general election, compared with three or four.
Inside, Trump was interrupted by hecklers as he spoke, including one man who waved a Mexican flag.
Opinion polls show Clinton & Trump in a tight race ahead of the 8 November US presidential election.
Clinton used the downing of an EgyptAir plane to say that Trump lacks the skills to bring together US allies.
Democrats urged Sanders on Wednesday to take a stronger stand against his supporters’ uprising in Nevada.
Trump said technology start-ups that had never earned a profit were able to sell shares at very high prices.
