Clinton was declared the projected winner in Washington D.C. by a number of news outlets, but she last week passed the delegate benchmark to clinch the nomination.
Her victory came just as Clinton and Sanders were meeting in Washington.
Sanders has not dropped out of the race, and on Tuesday he called for a “fundamental transformation” of the Democratic party. He has vowed to go all the way to the convention, but it’s unclear if that means he would contest the results or seek leverage on the party platform and party rules. He has called for the end of the system of “superdelegates,” the hundreds of elected officials and activists who are given delegate votes.
Earlier on Tuesday, his campaign sent a message to supporters announcing that he would take part in a live online video message on Thursday, with the cryptic line, “The political revolution continues.”