Members of the Bernie Sanders campaign blasted the media for reporting on the eve of major primaries Tuesday in California, New Jersey, and four other states that Hillary Clinton has secured enough delegates to clinch the Democratic nomination, saying the the Vermont senator intends to battle all the way to a contested national convention in July.

The Associated Press reported late Monday night that Clinton has reached the 2,383-delegate threshold needed to secure her party's nomination, becoming the first woman ever chosen as the presidential nominee of a major US political party. But her opponents immediately rebuffed the AP's assessment, pointing out that the tally includes 571 superdelegates, who can change their allegiance any time until the votes are officially cast at the Democratic convention on July 25.

"It is unfortunate that the media, in a rush to judgment, 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," Sanders spokesman Michael Briggs said in a statement.

Clinton has long been eager to put away her Democratic opponent and pivot to the general election against presumptive Republican nominee Donald Trump. On Monday night, she took to Twitter to say she was "flattered" by the AP's call, but that the campaign still had more primaries to win.

Voters in California, New Jersey, Montana, North Dakota, South Dakota, and New Mexico head to the polls on Tuesday, with a combined 694 pledged Democratic delegates at stake. Sanders campaign manager Jeff Weaver said that calling the race early for Clinton "threatens to suppress voter turnout" in these states, adding that high voter turnout in California especially, which has 475 pledged delegates up for grabs, will boost down-ballot Democrats in November.

"In California, a high voter turnout won't just mean a victory for our movement," Weaver wrote in an email to supporters Tuesday. "With large numbers of young people hitting the polls, we'll boost so many Democrats in major primaries that right-wing Republicans will be locked out of general election ballots for some of the most important House and Senate races of the fall."

Sanders has faced calls to concede the nomination early and start unifying the party, but a win for the Vermont senator in California would bolster his case for continuing to the fight through to the convention in Philadelphia, even though it's unlikely that a victory would provide him with enough delegates to close the gap with Clinton in any significant way. The Democrats use a proportional system of allocating delegates, which means a close contest between Clinton and Sanders in California would result in a near even split of pledged delegates. A polling average compiled by FiveThirtyEight has Clinton leading Sanders 48-43 in California.

Clinton supporters also hold that even if Sanders wins the popular vote, it's unlikely that superdelegates, who have a 15 percent stake in choosing the nominee, will jump ship. Earlier in March, half a dozen superdelegates in New York made waves and headlines after promising to back Clinton regardless of the results of the New York primary. Clinton ended up winning the New York contest, but Sanders supporters were disturbed by what they saw as an effort by the party establishment to disregard the will of voters.

At a press conference in Los Angeles on Saturday, Sanders once again proclaimed that "the Democratic National Convention will be a contested convention" if Clinton falls short of the requisite number of pledged delegates to win the nomination outright. His supporters have told VICE News they are also expecting a contested convention, and have backed the campaign's strategy to convince superdelegates to switch sides.

"It's definitely going to be a contested convention," said Kimberly Tregoning, a Sanders delegate from Kalamazoo, Michigan who will be attending the convention. "We know how imperative it is that we get there and we are able to present a case to the superdelegates that he's the better option going into a general election."

'It is unfortunate that the media, in a rush to judgment, 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.'

Another Sanders delegate from Washington State, Jessa Lewis, told VICE News she anticipated long days throughout the week-long convention that included hard discussions among party members and leaders about the party's future platform.

"Usually conventions are more like a beauty contests, but this year there's going to be more stuff that's being hashed out," she said. "There's going to be efforts to mold it into something more inclusive and figuring out how the party reflects and is inclusive of this new populist progressive movement that's coming in."

Clinton's lead in the polls in California shrunk in recent weeks as the Sanders camp has campaigned heavily across the state, but she is leading Sanders comfortably in polls in New Jersey, where 126 pledged delegates are up for grabs on Tuesday. The latest YouGov survey from early June put her 27 points ahead of her rival there.

Polls in New Jersey will be one of the first to close at 8pm ET. South Dakota's polls also close at 8pm, followed by Montana at 9pm ET and New Mexico at 10pm ET. North Dakota will also begin caucusing at 8pm ET. Voting booths in California will be the last to close at 11pm ET.

Late last month, Trump secured the magic number of delegates (1,237) needed to clinch his party's nomination. Some of those delegates included at least 95 delegates who are "unbound" to any one candidate. Republican members of Congress and party leaders have rallied around their presumptive nominee — some reluctantly — in an attempt to unify against Democrats and their prospective nominee.

On Monday, the White House indicated that President Barack Obama could also weigh in with an endorsement for a Democratic candidate as early as this week.

"The president intends certainly through the fall, if not earlier, to engage in this campaign," said White House spokesman Josh Earnest. "That's an opportunity the president relishes."

The Sanders campaign in recent weeks has pointed to national polling that places him well ahead of Trump in a general election match-up. Other polls show that Clinton would beat Trump in the same scenario, but by smaller margins. Trump has assailed Clinton, calling her "crooked Hillary" and saying she "has got to go to jail" for using a private email server during her tenure as secretary of state.

Clinton, however, has continued to beat Sanders nationally, winning 29 primary and caucus states compared with his 21. She also has secured 3 million more votes than the Vermont senator, as well as 291 more pledged delegates and 523 more superdelegates.

There is still a chance that Clinton could win enough pledged delegates to secure the nomination without the support of superdelegates on Tuesday. She would have to win 58.8 percent of all votes cast to surpass the 2,383 delegate threshold, according to the Washington Post. So far, she has scored around 56 percent of the vote across state primaries and caucuses.