Final contest of the often surprisingly close race comes amid fresh intrigue over Democrats’ next steps ahead of the party convention in Philadelphia next month

Bernie Sanders and Hillary Clinton met in Washington for talks on Tuesday night as the long, and often bitter, 2016 presidential nomination race drew to close with a win for the former of secretary of state in the DC primary.

Shortly after polls closed at 8pm, Clinton was projected to have won the small and largely symbolic Democratic contest, leading by a healthy margin of 79-21% at the time of the Associated Press declaration, with 90% of the vote counted.

She will add a majority of its 20 delegates to a commanding national lead that has already seen her declared the party’s presumptive nominee.

After a 14-month campaign that was largely aimed at taking on the Washington-based political class, Sanders was never expected to do well in the city and held just one rally for supporters here.

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The staunchly Democratic stronghold was also a closed primary, in which independent voters are unable to take part, and home to many African American voters – both factors that have favoured Clinton elsewhere.

But the final contest of the often surprisingly close national race between the two comes amid fresh intrigue over the party’s next steps ahead of a national convention in Philadelphia next month.

While voting was still going on, Sanders announced he would be holding a live video stream for supporters on Thursday night in which he said he would be discussing “what’s next for our campaign”.

“For the past 14 months, through the entire primary process, we’ve sent the establishment a message they can’t ignore: we won’t settle for the status quo,” said an emailed invitation. “After today, the voting is done, but our political revolution continues.”

The event is widely expected to mark the formal end of his candidacy for the nomination, but many see instead a call to arms among supporters to continue fighting for the policies that have often put him at odds with the party’s senior leadership.

At a press conference in Washington on Tuesday afternoon, the senator from Vermont also struck a defiant tone, refusing for now to endorse Clinton and telling reporters he would “fight as hard as we can” to transform the Democratic party.

“The American people are hurting and they are hurting badly. They want real change and not the same old same old,” he said, before calling on the party to replace Democratic National Committee chairwoman Debbie Wasserman Schultz.

“We need a person who is vigorously supporting and out working to bring people into the political process,” he said. “Yeah, I know that political parties need money, but it is more important that we have energy, that we have young people, that we have working-class people.”

He also called on the DNC to approve “a progressive platform that makes it crystal clear that the Democratic party is on the side of working people”, and repeated demands for electoral reform and more open primaries in future.

These issues were expected to come up in Tuesday night’s meeting with Clinton, held at the Capital Hilton hotel in Washington, along with other policy issues that Sanders is believed to want to see on the agenda before agreeing to back his rival and perhaps share his all-important voter mailing list.

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Nevertheless, relations behind the scenes appear to be thawing between Sanders and other members of the Democratic party.

At a lunch with the party’s senators on Capitol Hill, Sanders was said to have been well-received earlier on Tuesday.

“He got a standing ovation and a warm welcome back to the caucus,” Delaware senator Chris Coons told the Guardian. “I think his primary campaign had succeeded in engaging and mobilizing millions of average Americans, particularly working-class Americans who feel disaffected from our political process.”

Coons added: “My hope is he will take steps to continue his leadership in our caucus and continue to work hard, as he always has, on the issues that move him deeply and that he is passionate about.”