PHILADELPHIA — Hillary Clinton has played a key role at past Democratic National Conventions, supporting her husband’s two successful presidential campaigns and calling for unity to back President Barack Obama.

This time, it’s her convention.

“She’s moving from being in an important supporting role in the past to the starring role,” Rep. Steve Israel (D-Huntington) said Sunday, the day Democrats began arriving here for a weeklong convention to officially make Clinton their presidential nominee to take on Republican Donald Trump.

Eight years after losing the nomination to Obama, and just months after weathering a tougher-than-expected battle against Sen. Bernie Sanders of Vermont, Clinton is finally where she wants to be. No longer on the periphery but at center stage.

The four-day Democratic Party gathering will be her opportunity to connect with voters directly, said Sen. Chuck Schumer (D-N.Y.), especially on pocketbook issues that impact the middle class.

“When Clinton takes the stage to accept the party’s nomination,” Schumer said, “people will see her up close and real. Not filtered by the news media.”

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She will have marquee-name Democrats vouching for her — especially Obama, Sanders and her husband, former President Bill Clinton. All will tout her record, her experience and her signature issues. But by the end of the week, it will be on Hillary Clinton’s shoulders to make the case for getting elected in November.

“There’s a major difference in being a key player and being the player,” said Lawrence Levy, a political analyst at Hofstra University. “There’s far more pressure, personally, politically and logistically. No matter how many high-profile surrogates she has, it still comes down to her. She will have to make the case for making someone overcome their doubts and vote for her.”

As a Democratic loyalist, Clinton “has sown a lot of seeds on behalf of other candidates,” at all levels, Levy said, including getting her supporters to help Obama eight years ago. She is hoping that pays off this week and over the next four months, Levy said.

“Now it’s time for her to reap the benefits of that loyalty,” Levy said. “She’s raised tens, if not hundreds of millions, of dollars for people running for everything from county executive to president. This is the week this loyalty comes due.”

Clinton supporters said the party will unite behind an upbeat message about the economy and an optimistic view of America’s future, which they said will contrast with Trump’s dark tones.

“In contrast to the gloomy, terrifying picture Mr. Trump paints, I think you’ll hear a very positive message,” said Rep. Carolyn Maloney (D-Manhattan), adding that the nation has added some 14 million jobs under Obama’s tenure and the Dow Jones stock index rocketed.

She said the convention also will highlight Clinton’s experience at dealing with world leaders and tackling complicated issues.

“She will have specific proposals, not just a ‘Trust me, I’ll fix everything,’ ” Maloney said in a not-so-veiled swipe at Trump’s claim that he is the “only one” who can fix the nation’s woes.

“The three key objectives of the convention will be: contrast, contrast, contrast,” Israel said. “You’ll see a contrast with that angry, dark, divisive frothing at the Republican convention, with a Democratic vision that is unified and optimistic.”

But already there were signs of turmoil around the edges.

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Rep. Debbie Wasserman Schultz (D-Fla.) was forced out as Democratic National Committee chairwoman Sunday after a WikiLeaks report showed the organization tilted in favor of Clinton — at Sanders’ expense — during the primary season.

Also, Sanders’ supporters held not one but two protests Sunday; one for a clean energy agenda to be included in the Democrats’ party platform and the other against the DNC and Wasserman Schultz. Many in the streaming crowd of protesters wore Sanders shirts and buttons, and carried signs critical of Clinton, including “Stop the Clinton Crime Spree.”

Dawna Demster, 50, an activist from Atlanta, said she remained a loyal Sanders supporter and his supporters wanted to continue to show they would remain active in pushing the ideals he touted on the campaign trail.

“I’m here today to ensure that our needs, the needs of we the people, are not swept under the rug by corporations,” Demster said.

With Laura Figueroa and Maria Alvarez