Hillary Clinton had her historic moment. Next step: Get Sanders supporters on board.

Reporting from Brooklyn, N.Y. —  Buoyed by Hillary Clinton’s clinching of the nomination and her double-digit victory in the California primary, Democrats jump-started efforts to close ranks behind her Wednesday for a five-month campaign to prevent Donald Trump from reaching the White House.

Their biggest challenge was how to approach the candidacy of her primary opponent, Bernie Sanders. For Democrats to marshal all of their resources against Trump, Clinton needs a united front, one that eludes her until the Vermont senator drops out.

Clinton stayed off the campaign trail Wednesday after delivering a triumphant and at times emotional victory speech in Brooklyn, N.Y., the night before, where she alluded to her own defeat in the Democratic primary eight years earlier. In a series of media interviews, she said she was eager to bring Sanders’ backers on board, particular younger voters.

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“Anyone who supported Bernie Sanders who thinks we should raise the minimum wage, who thinks that we should have universal healthcare coverage, who thinks that the wealthy have not paid their fair share would certainly not find that Donald Trump’s views are in line with theirs,” she said on ABC.

Her campaign, meanwhile, instructed top allies to avoid opining publicly on what Sanders should do next, to give him space to decide himself.

Asked whether they had asked for or expected Sanders to concede, Clinton campaign manager Robby Mook said it was too early for such a request.

“This is an important period for Sen. Sanders to, first of all, probably get some sleep, but second of all to step back and assess where they are,” Mook said in an interview Wednesday. “I think he needs some time to thank his supporters and get the lay of the land and make decisions about how he wants to move forward.”

Ultimately, though, he predicted that Sanders would work with Clinton to help defeat Trump.

“We have a lot of work to do and a lot of outreach to do” to unify the party, Mook said. “But both our campaign and Sen. Sanders and his campaign are completely committed to making sure that the White House remains in Democratic hands this fall.”

The White House said Wednesday that while President Obama considered Clinton to be the party’s nominee, he would wait to endorse her until after he met with Sanders on Thursday, an encounter scheduled at the senator’s request.

Appearing on “The Tonight Show” during a fundraising visit to New York, Obama told host Jimmy Fallon for an episode to air Thursday that the contested primary was healthy and made Clinton a better candidate.

“My hope is over the next couple weeks we’re able to pull things together,” he said.

Top Democratic congressional leaders said they were confident Sanders would unite behind Clinton.

“We’re on a path to unity,” said Sen. Charles E. Schumer of New York. “The Democratic Party will shortly be unified for two reasons: One, we know what would happen if there were a President Trump. And two, we know the good things that would happen — getting middle-class incomes moving, bringing America together — if there’s President Clinton.”

Some of Sanders’ top allies expressed confidence he would act in the interests of the party even as they sought to preempt efforts by Democratic leaders to push him aside before he was ready to exit the race on his terms.

“The reality is unattainable at some point,” Rep. Raul M. Grijalva (D-Ariz.), a Sanders backer, told the Washington Post. “You deal with that. Bernie is going to deal with this much more rapidly than you think.”

Sanders, for now at least, is pressing ahead with plans to compete in the final primary battle of the year, next week in the District of Columbia. But his remarks Tuesday in Santa Monica indicated his campaign is about issues as much as about his own shot at the presidency.

“Our fight is to transform this country and to understand that we are in this together,” he said, “to understand that all of what we believe is what the majority of the American people believe and to understand that the struggle continues.”

While far short of locking arms to sing “Kumbaya,” the relative Democratic harmony represented welcome progress just weeks after the unrest at a state convention in Nevada prompted some of the sharpest intraparty sparring of the campaign, and heightened concern that it would carry into the convention in Philadelphia.

It also stood in stark contrast to Republicans who are openly pleading with their presumptive nominee to soften his tone, or in some cases turning their back on his candidacy altogether.

Mook predicted that Democrats would distinguish themselves for voters from “a Republican Party that’s really contorting itself to try to align with a candidate who has not only managed to offend virtually everyone in this country but whose temperament is so erratic it’s hard to stand behind him.”

Despite nervous moments and some self-inflicted struggles, Clinton emerges from the Democratic nomination fight in a stronger position than even Obama was in 2008. She won 13 of the final 19 contests, including four of six on Tuesday, giving her a pledged delegate advantage of more than 300 – three times what Obama enjoyed.

Steve Schale, a Democratic strategist who served in key roles in both Obama campaigns in the swing state of Florida, recalled how in 2008 the then-Illinois senator had to work overtime in the weeks after Clinton’s concession to repair relationships with her top donors and supporters in the state.

“How we approached it eight years ago was ensuring that folks who had supported Hillary Clinton knew that our success was based on their involvement,” he said.

Democrats are eager to quickly turn to the fight against Trump. Clinton already has announced plans to campaign next week in two November battlegrounds, Ohio and Pennsylvania.

Sanders will make his own decision on his own timeline, predicted Stephanie Schriock, president of the Emily’s List fundraising group, which endorsed Clinton.

“This is a time where not just Democrats, but independents and moderate Republicans — Republicans with common sense — have to come together, because the stakes are so incredibly high,” she said.

Times staff writers Lisa Mascaro in Washington and Christi Parsons in New York contributed to this report.

michael.memoli@latimes.com

For more campaign coverage, follow @mikememoli on Twitter.

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UPDATES:

4:53 p.m.: This story was updated with comments from President Obama.

3:03 p.m.: This story was updated with new details and comments throughout.

This article was originally published at 7:51 a.m.