Hundreds of Bernie Sanders supporters and other protesters took to the streets of Philadelphia on the first day of the Democratic convention on Monday, filling the air with chants of "Nominate Sanders or lose in November!" and "We are the 99 percent!" Pro-Sanders demonstrators aired their frustrations over issues ranging from climate change to free trade to economic justice - but first and foremost, over the "rigged" electoral process that they believe robbed the Vermont senator of his rightful nomination as the Democratic presidential nominee. "I am angry, I'm angry at the Democratic establishment," Corey Collier, an organizer for the activist umbrella organization Philly.