Bernie Sanders will vote for Democratic rival Hillary Clinton in November's US presidential election, but stopped short of endorsing the former secretary of state in an interview on Friday with MSNBC.
"I think the issue right here is I'm going to do everything I can to defeat Donald Trump," Sanders said. "I think Trump in so many ways will be a disaster for this country, if he were to be elected president."
But the Vermont senator said he would not yet withdraw from the race, despite Clinton having secured the required number of delegates to be the party's nominee.
"Why would I want to do that when I want to fight to make sure that we have the best platform that we possibly can, that we win the most delegates that we can?" he said.
Sanders had met with Clinton this month to discuss the way forward for his campaign after she secured the nomination.
He has stepped back from previous vows to continue to fight to win over party officials in a bid to pry the nomination from Clinton, but has remained reluctant to end his campaign as he seeks to influence the party platform.
"What my job right now is is to fight for the strongest possible platform in the Democratic convention," he said. "And that means a platform that represents working people that stands up to big money interests and that's what we're trying to do."
Sanders is a self-identified democratic socialist and has been a political outsider throughout his career, serving in the Senate as an independent. His political rise in the Democratic Party primaries seemed to surprise even him as voters identified with his economic populism.
Presumptive Republican nominee Trump has sought to win over disaffected Sanders supporters, claiming his anti-establishment views are a better fit for those voters than Clinton, who has been part of the political establishment for decades.
Sanders won 22 of 56 Democratic Party primaries or caucuses but finished with far fewer delegates than Clinton, whose lead in so-called superdelegates was enough to make her the presumptive nominee after the last round of state-by-state voting on June 7.
Sanders, whose campaign exceeded nearly all expectations largely with support from people 45 years or younger, will take more than 1,900 delegates to the party's convention next month in Philadelphia.