washington bernie sanders promise thursday work presumptive democratic presidential nominee hillary clinton defeat republican donald trump nov. election formally pull race white house sanders endorse clinton online speech supporters make clear shift focus build grassroots movement fight liberal policy agenda transform democratic party major political task face next five months make certain donald trump defeat defeat badly personally intend begin role process short period time u.s. senator vermont say also look forward work secretary clinton transform democratic party become party work people young people wealthy campaign contributors say speech broadcast hometown burlington vermont sanders resist pressure democrats exit white house race back clinton since clinch party nomination last week say would keep fight goals reduce income inequality remove big money politics rein wall street defeat donald trump goal must continue grassroots efforts create america know become say must take energy democratic national convention july 25 philadelphia 1,900 delegate sanders keep campaign alive leverage force concessions clinton policy goals deliberations party issue platform reform seek democratic party nominate process lay staff stop campaign drop plan court unbind delegate unspoken acknowledgment former secretary state nominee sanders meet clinton tuesday night nominate process end say would continue discussions campaign make certain democratic party pass progressive platform history democrats actually fight agenda vision future country kind fringe idea radical idea mainstream millions americans believe want see happen sanders say sanders vow help clinton beat trump keep campaign alive