Hillary Clinton’s declining personal image, ongoing battle to break free of the challenge from Sen. Bernie Sanders and struggle to adapt to an anti-establishment mood among voters this year have become caution signs for her campaign and the focus of new efforts to fortify her position as she prepares for a bruising general election.

More than a dozen Clinton ­allies identified weaknesses in her candidacy that may erode her prospects of defeating Donald Trump, including poor showings with young women, untrustworthiness, unlikability and a lackluster style on the stump. Supporters also worry that she is a conventional candidate in an unconventional election in which voters clearly favor renegades.

“I bring it down to one thing and one thing only, and that is likability,” said Peter Hart, a Democratic pollster who has conducted a series of focus groups for the Annenberg Public Policy Center at the University of Pennsylvania.

To counter these challenges, Clinton is relying primarily on the prospect that her likely Republican opponent’s weaknesses are even greater. But advisers also are working to soften her stiff public image by highlighting her compassion and to combat perceptions about trustworthiness and authenticity by playing up her problem-solving abilities.

“Hillary Clinton is in a stronger position than Donald Trump, but it will be competitive,” said Joel Benenson, Clinton’s senior strategist and pollster. “All these races are.”

Democratic presidential candidate Hillary Clinton said she's "never heard such reckless, risky talk" about nuclear weapons from a future presidential nominee than from Donald Trump during a rally in Louisville, Ky. (Reuters)

None of these Democrats said they expected Clinton to lose — but many said she could. For the most part, it is her qualities as a candidate that keep her allies up at night, not her fitness to be president, which they categorically do not question. They also lament how exposed these flaws have become during a long primary contest against Sanders, who has profited from suspicion and dislike of Clinton among ranks she now must win over.

Although Clinton has never trailed Sanders in the delegate count and is all but assured of securing the nomination in June, she is widely expected to lose more Democratic primaries this month, which could amplify her weaknesses.

When Democrats assess Clinton, they tend to zero in on her communication skills: She is scripted and thin-skinned, they say. And with a sigh, they acknowledge the persistent feeling among a lot of Americans that they just don’t like her. Polls long have shown that many voters do not trust Clinton and that a majority view her unfavorably.

Hart said being seen as likable is “about the lowest bar” for a candidate, and yet Clinton has lower likability numbers today than she did when the campaign began.

It is cold comfort that Trump’s are worse, several Democrats said.

Among other potential problems identified by supporters: Clinton’s unpopularity with white men, questions about whether her family philanthropic foundation helped donors and friends, and lingering clouds from her tenure at the State Department, including her private email system, the Benghazi attacks in which four Americans were killed and her support for military intervention in Libya.

Aides say Clinton will continue to speak of her State Department years as evidence of her national security credentials. They point to 11 hours of congressional testimony about Libya and Benghazi, and a willingness to acknowledge mistakes, as proof that she is dealing with those issues forthrightly.

There are also concerns particular to an election against Trump. How, several Democrats asked, should Clinton deal with such an unpredictable antagonist? Supporters see potential problems for her in Trump’s omnipresence in American media, while she neither likes nor excels at media interviews.

They said there are upsides and downsides to Trump’s insults and taunts, including those having to do with her husband’s past infidelities.

If Trump continues to call Clinton an “enabler” of her husband’s behavior, her supporters see an opportunity to outclass her opponent.

“I couldn’t believe it!” Clinton supporter Sen. Dianne Feinstein (D-Calif.) said last week of Trump’s attacks. “You blame the woman for male infidelity? I mean, to me, it was kind of bizarre. You would visit the sins of one on the other? I don’t think there’s any woman in America who doesn’t understand that is wrong.”

Bill Clinton himself is a ­double-edged sword, longtime supporters said. Hillary Clinton has no better advocate, and one who is now working at a furious pace to rally Democrats in the last primary contests. But with his own prodigious political talents, the former president also shows up his wife’s shortcomings on the stump, even if inadvertently, and is perhaps even more prone than she to going off script when someone gets under his skin.

Another challenge, two people who know her well said, will be to show how Hillary Clinton can tackle issues people care about without letting her wallow in weedy policy details. Clinton is a self-identified wonk, a believer in the power of government and what she sometimes calls ­evidence-based approaches to solve problems. This does not often make for good political theater.

“She’s horrible at running, but she’s fantastic at governing,” a longtime friend and supporter said. “She will roll up her sleeves. That’s not just a campaign talking point.”

The campaign is making an effort to highlight Clinton’s compassion. For example, an ad shows her consoling a 10-year-old who is worried about her family being deported. “You let me do the worrying,” Clinton says, hugging the girl.

Similarly, the campaign has sought to address qualms over Clinton’s trustworthiness and what voters have termed her “authenticity” by portraying her as the candidate with the best interests of individual Americans and the country at heart.

A vice-presidential pick who is a rousing speaker and possesses strong populist Democratic credentials is one potential antidote to Clinton’s to-do-list style on the stump, Democrats said. Some of the names mentioned, including Sen. Elizabeth Warren of Massachusetts, Sen. Cory Booker of New Jersey, Sen. Timothy M. Kaine of Virginia and Labor Secretary Thomas E. Perez, fit those bills. A campaign aide said Clinton is open to an unconventional candidate and does not rule out an all-woman ticket.

President Obama, whose “Yes, we can” mantra perfectly captured the 2008 political moment, is another potential solution to Clinton’s message problem and lack of mass appeal. Obama is expected to begin campaigning for Clinton in earnest as early as June, when she is expected to lock up the nomination.

Others said there is only so much Clinton can do to address her skills on the stump or to alter perceptions that have formed over nearly three decades in the public eye. Sexism and unfair expectations play a role, several of her partisans said, as the country adjusts to having a woman at the top of a national ticket — and so does the fact that nearly every American already has an opinion about the woman in question.

“They’re dealing with 20 years, almost 30 years now, of public narratives about her,” said Dan Pfeiffer, former White House senior adviser in the Obama administration. “I don’t think that’s fixable in the next six months. You have to turn it from a referendum on her trustworthiness to a contrast.”

Clinton has said that it pains her to hear that people don’t like her but that all she can do is make her case that she would be a good president. Some of her allies said she should focus on things she can control rather than on the subjective measure of likability.

“What I want to happen are things that will never happen,” said one longtime Clinton family supporter and donor who requested anonymity to express criticism of something he said Clinton probably could not change even if she wanted to. “I mean, we can’t give her an injection to make her an energetic candidate.”

Some strategists, including Benenson, argue that as the primaries end and Democrats begin to unify behind their nominee, her ratings will begin to improve.

Several other veterans of past campaigns said that, although Clinton will suffer from an authenticity gap against Trump, in the end voters will choose a more guarded personality to occupy the Oval Office.

“When the true Hillary Clinton and the real Donald Trump are revealed to Americans, there is no way the American people are going to pick the petulant 12-year-old,” said Bill Burton, a former senior Obama strategist.

Attacking Trump will be a big part of Clinton’s fall strategy. Numerous allies noted that Clinton is at her political best when fighting and at her most sympathetic when seen as vulnerable or a victim. One campaign strategy to address perceptions that she is remote or robotic is to “let ’er rip,” as one supporter said. ­Another will be to draw contrasts with what her allies describe as Trump’s nastiness and narcissism.

At a rally Tuesday in Louisville, Clinton accused Trump of running the most divisive campaign she has ever seen and said she looks forward to debating him.

“People say, ‘Well, maybe he doesn’t really mean it,’ ” she said. “If you are running for and serving as president, you better mean what you say.”

Also last week, Clinton, with obvious relish, compared herself with Trump on the subject of who had been more transparent in the release of tax records. She and her husband have placed 33 years’ worth in the public domain, she crowed.

“We’re going to find out” why Trump hasn’t released any returns, she said.

Benenson said the tax returns are emblematic of the downside of Trump’s outsider candidacy. Voters can extrapolate many things from Trump’s refusal or reluctance to release the records, including that he thinks regular political rules don’t apply to him, Benenson said.

“His unconventional candidacy is a challenge” for Clinton, “but it creates problems for him, too,” Benenson said. “The American people know they are electing the commander in chief. He’s an unconventional candidate, but he’s also a risky, dangerous candidate when it comes to people’s economic lives and safety and security abroad.”