BURLINGTON, Vt. — Democratic presidential candidate Bernie Sanders said Thursday in an address to his supporters that he will work with Hillary Clinton to transform the Democratic Party, adding that his ‘‘political revolution’’ must continue and ensure the defeat of Republican Donald Trump.

Sanders said in a capstone address to his political followers online that the major task they face is to ‘‘make certain’’ Trump is defeated. The Vermont senator said he plans to begin his role in that process ‘‘in a very short period of time.’’

‘‘But defeating Donald Trump cannot be our only goal. We must continue our grassroots efforts to create the America that we know we can become,’’ Sanders said in remarks prepared for delivery. ‘‘And we must take that energy into the Democratic National Convention on July 25 in Philadelphia. where we will have more than 1,900 delegates.’’