Hillary Clinton has clinched the Democratic Party nomination for US president after reaching the required number of delegates, according to AP.
The news agency’s tally puts Mrs Clinton on 2,383 – the number needed to make her the presumptive nominee.
She will become the first female nominee for a major US political party.
Vermont Senator Bernie Sanders, her rival for the nomination, said he intended to stay in the race until the party’s convention in July.
Mrs Clinton reached the threshold with a big win in Puerto Rico and a burst of last-minute support from party insiders called superdelegates, AP said.
At an appearance in Long Beach, California, shortly after the news broke, she said: “We are on the brink of a historic and unprecedented moment but we still have work to do.
“We have six elections tomorrow and we’re gonna fight hard for every single vote, especially right here in California.”
Voters will go the polls for Democratic primaries tomorrow in California, Montana, New Mexico, North Dakota, South Dakota, and New Jersey.
Superdelegates pledge their support for a candidate ahead of the convention but do not formally vote for them until the convention itself.
The nominee for either party is not officially named until the parties’ respective conventions.
Mr Sanders’ campaign team said the Vermont senator would attempt to win back superdelegates who have pledged their support to Mrs Clinton.
Mr Sanders’ spokesman Michael Briggs said that calling the Democratic contest before the superdelegates formally vote at the convention was a “rush to judgment”.
“Our job from now until the convention is to convince those superdelegates that Bernie is by far the strongest candidate against Donald Trump,” he said.
Mrs Clinton, a former secretary of state, New York senator and first lady, leads Mr Sanders by three million votes, 291 pledged delegates and 523 superdelegates, according to AP’s count.
She won 29 caucuses and primaries to his 21 victories.
That gives her a significantly greater lead over Mr Sanders than Barack Obama had over her in 2008 – he led by 131 pledged delegates and 105 superdelegates at the point he clinched the nomination.