Now it’s the Democrats’ turn.

The Democratic Party, which gathers Monday in Philadelphia, is likely to spend the next four days describing a country far different from the dark dystopia sketched by Republicans in Cleveland, especially by presidential nominee Donald Trump in his acceptance speech.

Democrats do believe there are serious problems to be solved, but a party that wants to keep the White House can’t run against the person in it. So theirs will be a more hopeful and optimistic message. And the party will put more star power onstage to deliver that message.

But the feel-better flavor that will be mustered by the Democrats cannot mask the party’s own significant troubles. Its presidential candidate is flawed and deeply distrusted. It has suffered massive election losses at the state and federal legislative levels. And it has had difficulty connecting with white working-class voters in particular, once the bedrock of the party.

The Democrats must address all three to remain a vital force in American politics, a task that begins in Philadelphia.

Hillary Clinton’s central mission is to convince voters that they can trust her. That’s a high bar to clear. Put aside the incessant “Lock her up!” chants in Cleveland — many in her own party are queasy over the email scandal and other missteps. Reducing that deficit of trust cannot be accomplished in the four-day span of a convention nor, most probably, in the three months left in this campaign. So she’ll need to convince voters that her competence and experience are worth supporting, and that she will win back their trust with her performance in the White House.

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Clinton could be helped by her selection of Virginia Sen. Tim Kaine as her running mate. He’s steady, smart and moderate, fluent in Spanish, and capable of stepping in as president. He’s also a safe choice, and highlights Clinton’s unwillingness to take risks.

As tempting as it will be to attack Trump, that’s a strategy to simply win a presidential election. There is much more at stake for Democrats. Clinton must convince voters that the Democratic platform, by some measures the most progressive platform the party ever has had, speaks to their concerns. The preamble to the platform, which was hashed out by supporters of Clinton and primary rival Sen. Bernie Sanders and must be adopted formally at the convention, dives right into the dilemma. It extols President Barack Obama’s work in leading a recovery from the Republican-created Great Recession while acknowledging that “too many Americans have been left out and left behind.”

To remedy that, the party proposes a host of sensible measures that should appeal to many of those middle- and working-class voters who find themselves adrift. They include an expansion of Social Security, a $15 minimum wage, 12 weeks of paid family and medical leave, and a public option added to Obamacare.

But there is a difference between doing what is necessary and what is sufficient, a difference especially critical in this election. The Democratic Party also must deal with voter anger over government ineptitude and political corruption. That frustration fueled the campaigns of Trump and Sanders, and it has not dissipated. If anything, it seems likely to intensify among Sanders’ supporters in Philadelphia after an email dump Friday revealed that Democratic National Committee officials who favored Clinton worked to undermine Sanders’ campaign during the primaries.

Voters want change, and Democrats are offering someone seen as a longtime, tightly connected, ethically conflicted insider. Clinton’s claim that being a woman makes her an outsider rings hollow to these voters.

Sanders attacked this effectively in the primaries, rallying his supporters around the idea that Clinton was neither pure enough nor progressive enough, that the Democrats seemed almost to be two parties. Clinton beat back that challenge, maintaining that her goals were more achievable while embracing some of Sanders’ progressiveness. It was a smart strategy and a delicate tightrope to walk. But it reinforced complaints that she will do and say whatever it takes to become president. Add that to her tasks: She must convince voters, including many in her own party, that she truly believes what she’s advocating.

But for the party to expand beyond its base of blacks, Hispanics, and Northeast and West Coast liberals, it will have to traverse several tightropes — such as convincing voters that reasonable gun control measures will not weaken their Second Amendment rights, that it is essential to protect both police officers and minorities from senseless violence, and that embracing immigration reform does not mean putting American citizens out of work. All three are essential to help move the country forward.

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These challenges are not easy to meet with an increasingly polarized electorate. The Democratic Party is wise to emphasize breaking down barriers and building bridges as the more strategic path to leaping these hurdles.

The next four days will begin the party’s attempt to convince voters that these are better choices than isolation and fear.