PHILADELPHIA — It’s now or never for Hillary Clinton to connect.  

In her biggest speech as a candidate, the former first lady, former senator and former secretary of state will try to convince voters that she is the woman for the current moment in American history — that she’s the one they want in the Oval Office.  

For all of Clinton’s many strengths and skills, this has been her enduring weakness: She’s not very good at drawing a straight line from her values to a vision for the country that is about something greater than her ambition. Or, at least, she has not managed to convince a broad swath of the electorate of that.  

“It’s a chance to talk in personal terms about her history and beliefs and how it connects with what she’s fighting for now,” said one longtime Clintonworld insider. “She can also highlight the values of her life and campaign in the context of some of the issues that are defining the election, as well as much of her career.”  

Clinton aides and advisers say her slogan, “Stronger Together,” will be front and center. It’s a meh slogan — like most Clinton speeches, it’s solid enough but unspectacular. But the duality is the key to the case she’ll make Thursday night and through November.  

Clinton isn’t just selling herself as someone who believes that America’s at its best when it’s inclusive. She’s also pointing out her belief that Donald Trump’s divisiveness would weaken the nation’s standing.  

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Hillary’s Honesty and Trump’s Temperament

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“She’s going to lay out the real moment of reckoning America faces, and make the case that we can’t let ourselves be torn apart,” said Jess McIntosh, a spokeswoman for the campaign. “We have to work together and rise together.”  

Think of it like the slogan Barack Obama used when he ran against her in 2008: “Change We Can Believe In.” The flipside, of course, was the core argument that Clinton was stuck in the past and dishonest.  

Trump has essentially adopted those lines of attack against Clinton, promising big changes and bestowing on her the sobriquet “Crooked Hillary.”  

Clinton has struggled for the entirety of the campaign to overcome the perception that she’s a liar, and Democrats here say they want to hear her address that charge, to explain herself better. That’s a big risk for a convention speech — a vessel that’s typically all positive about the candidate — but it’s also a gamble for her to remain silent on the character issue that has acted as an ever-growing weight on her campaign.  

Just when it looked like Clinton’s honest-and-trustworthy ratings couldn’t get any worse, FBI Director Jim Comey made clear that things she’d said in public about her private email server simply weren’t true. For someone already battling a reputation for dissembling, it was a deep cut that managed to send the percentage of Americans who don’t find her honest upward.  

That figure is now over two-thirds.  

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Thanks, GOP, XOXO, Hillary

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Whether it’s a direct confrontation of the honesty question or a more circuitous attempt to gain credibility, Clinton has to find a way to make persuadable voters believe her — and believe in her — or they’ll simply judge everything she says to be untrue.  

She’ll also have to get buy-in from the Bernie Sanders die-hards in the arena and at home — or at least, a good number of them. And she’ll want to fire up her base — women, particularly women of color — by finding a way to artfully frame her historic nomination as a victory she won for a cause greater than herself.  

After the 2008 primary, Clinton delivered speeches in which she used two black women — Sojourner Truth and Harriet Tubman — to point to the commonalities of the civil rights movement and the women’s rights movement. It was a way of getting her supporters to invest in the Obama campaign and the chance to make history with the first black president, even though they had hoped to do so by electing a woman to the nation’s highest office.  

Now, she wants fellow Democrats — and independents and some Republicans — to take ownership of a campaign that would shatter what she once called “the highest, hardest glass ceiling” of them all.  

“This is not just a personal achievement,” said the veteran Clinton insider. “It says something about the progress of our country.”  

Clinton faces a serious narrative challenge in her convention speech and throughout the rest of the campaign — and it’s one that, at least until now, she hasn’t been able to resolve.  

To elevate herself, she’ll have to weave her life story into the fabric of American aspiration, present her values as those of the electorate and pull together a coalition that spans the Democratic Party and part of the universe of Republicans and independents.  

She says Americans are “stronger together.” The question is whether she can unify them. And this high-stakes speech will either answer that in the affirmative or leave Clinton no closer to the presidency than she was when the Democrats opened their convention on Monday.  

Roll Call columnist Jonathan Allen is co-author of the New York Times-bestselling Clinton biography “HRC” and has covered Congress, the White House and elections over the past 15 years.