Nicole Gaudiano

USA TODAY

WASHINGTON — Sen. Bernie Sanders isn’t giving up, at least for now, though the end appears to be coming near.

Hours after Hillary Clinton declared herself the winner of the Democratic nomination, Sanders pledged to continue his fight through the last primary on June 14 in Washington, D.C., where he will hold a rally Thursday, and then at the Democratic Party's convention in Philadelphia next month.

"I am pretty good in arithmetic and I know that the fight in front of us is a very, very steep fight," he told cheering supporters at an election night rally in Santa Monica. "But we will continue to fight for every vote and every delegate ... The struggle continues!"

The Associated Press announced Monday night that Hillary Clinton had secured support from enough delegates to win the Democratic nomination, and Tuesday she took the stage after a big victory in the New Jersey primary and declared the race over. Clinton was the winner in the South Dakota and New Mexico primaries and Sanders the winner in Montana's primary and North Dakota's caucus. The AP, CNN and NBC all called California for Clinton early Wednesday.

Sanders' delegate deficit has long been all but insurmountable. Clinton's campaign claimed a majority of the pledged convention delegates, though she will still need superdelegates to put her over the top for the nomination. The New York Times reported Tuesday that Sanders plans to lay off at least half his campaign staff on Wednesday, citing sources close to the campaign.

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The White House announced on Tuesday night that President Obama will meet with Sanders — at the senator's request — on Thursday to continue discussing issues at stake in the election for working families. Obama called both Sanders and Clinton to congratulate them on their campaigns. He congratulated Clinton for securing the delegates necessary to clinch the Democratic nomination.

During his remarks, Sanders said he looks forward to working with Obama "to make sure that we move this country forward." His supporters booed when he said he received a "very gracious call" from Clinton and he congratulated her on her victories in Tuesday's contests.

Sanders' campaign continues to maintain some superdelegates — who may support the candidate of their choice — will switch their allegiance from Clinton to Sanders at next month's Democratic National Convention in Philadelphia.

"Superdelegates have a very important decision to make," Sanders told Lester Holt on NBC Nightly News on Tuesday. His supporters are calling superdelegates now, hoping to convince them he would do better than Clinton against GOP presumptive nominee Donald Trump in November.

Sanders laughed when Holt said that strategy defies history and the will of voters.

"Defying history is what this campaign has been about," he said.

Clinton, in declaring herself the Democratic nominee Tuesday night, celebrated the historic nature of her own achievement and congratulated Sanders on running an "extraordinary campaign."

"He has spent his long career in public service fighting for progressive causes and principles and has excited millions of voters, especially young people," she said. "Let there be no mistake, Sen. Sanders, his campaign and the vigorous debate that we’ve had about how to raise incomes, reduce inequality, increase upward mobility have been very good for the Democratic party and for America."

Key to his strategy had been winning in California — where he has campaigned for weeks — and performing well in Tuesday's other nominating contests. Sanders hoped a strong showing could keep his campaign alive and help him make his case to superdelegates that he's preferable to Clinton.

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But the timing of the AP announcement was a problem for Sanders. He said he was "upset" and "disappointed" with the Associated Press for "hounding" superdelegates to anonymously say whom they support. Sanders said Tuesday on NBC he was worried the AP's announcement would suppress voter turnout.

The campaign acknowledged as much in an email to supporters, seeking contributions and volunteers to call California voters.

“Pundits and the political press want to call this race early before every last person votes,” Jeff Weaver, Sanders’ campaign manager, wrote in the email on Tuesday. “That threatens to suppress voter turnout in New Jersey, California, North Dakota, South Dakota, Montana and New Mexico. But we’re not going to let that happen.”

In a Monday night statement, Sanders' spokesman, Michael Briggs, said Clinton can't claim the nomination based on pledged delegates alone, and he repeated the campaign's argument that more than 400 superdelegates endorsed her before the first caucuses and before any other candidate had entered the race. Fact checkers have pointed out that is not correct; The Washington Post noted that the AP's first formal delegate tally was in November, long after Sanders had entered the race.

“It is unfortunate that the media, in a rush to judgement, are ignoring the Democratic National Committee’s clear statement that it is wrong to count the votes of superdelegates before they actually vote at the convention this summer,” Briggs said.

The Sanders campaign has yet to win over any Clinton superdelegates. But Sanders' campaign manager, Jeff Weaver, told Chuck Todd on MSNBC on Tuesday the campaign's superdelegate outreach will intensify in the coming weeks.

"A lot of superdelegates, really, frankly, they want to see how the primaries and caucuses turn out," Weaver said. "They know they have time between the end of that process and the convention."

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