WASHINGTON -- Bernie Sanders called for a wholesale transformation of the Democratic Party on Tuesday, the day of its last primary, signaling what he'll fight for leading up the party's national convention next month.

The independent senator from Vermont laid out his vision of how the Democratic Party could become more democratic at a press conference outside of his campaign headquarters, just hours before he was set to meet privately with Hillary Clinton . Clinton secured enough delegates to win the party's nomination last week, rendering the District of Columbia's presidential primary on Tuesday irrelevant to the outcome of the race. Sanders has yet to concede; he said as recently as Sunday that he would remain in the race until the convention.

The first thing Sanders did at his press conference was to demand new leadership at the Democratic National Committee. Sanders endorsed and raised funds for Tim Canova , a Florida law professor challenging DNC chair Rep. Debbie Wasserman Schultz (D-Fla.), after months of criticizing her for what he said were blatant moves to rig the primary process in Clinton's favor.

"How do we revitalize the Democratic Party? How do we make it easy for people to participate politically, rather than have one of the lowest voter turnouts of any major country on earth?" Sanders asked, rhetorically.