As the presidential candidate with the lengthiest political career, former vice president Joe Biden faces the formidable challenge of defending his long record and long-held beliefs while updating them for today’s realities. Foreign policy is no exception. On Thursday in New York, Biden will lay out a vision for a return to a traditional U.S. foreign policy in a speech that ostensibly takes aim at President Trump but really has middle-class voters in mind.

Biden, the Democratic front-runner, will lay out his case for returning the United States to its traditional role as the leader of a world order based on promotion of democracy, multilateralism, alliance-building and diplomatic engagement. He will also attempt to shape his policies to address the grievances of those inside his own party who support a more progressive, less interventionist approach.

“There’s a very stark recognition that the world has changed, we are not going back to the way we did things,” Antony Blinken, one of Biden’s chief foreign policy advisers, told me during an interview on Wednesday. “There are certain basic principles that worked before and should work again, but it’s very clear that the world is different, including from when [the Obama administration] found it in 2008. We need the foreign policy for the world as we find it today and also as we anticipate it for tomorrow.”

First and foremost, Biden will call out the recklessness and dysfunction of Trump’s foreign policy approach, accusing the president of posing an existential threat to American moral and international leadership. He will present the 2020 election as the last chance to save what’s left of the United States’ moral and international credibility and respect.

Beyond that, Biden is proposing a platform that largely tracks the neoliberal-lite foreign policy approach he has believed in for the past several decades — with some updates, and a few gaps. Biden’s lifetime collection of foreign policy credentials contains both assets and liabilities, and his campaign hasn’t worked through how to deal with them all just yet.

The Democratic Party faces the same fissures as the GOP, specifically the split between centrist, internationalist, free-trading democracy advocates and far-left (or far-right) populists who are agnostic on values promotion and skeptical about military intervention. Several of Biden’s primary opponents have laid out decidedly progressive foreign policy platforms, including Sens. Bernie Sanders (I-Vt.) and Elizabeth Warren (D-Mass.).

On the more centrist track are figures such as Sen. Amy Klobuchar (D-Minn.), former Maryland congressman John Delaney and South Bend, Ind., Mayor Pete Buttigieg. Biden is naturally part of this camp, but he’s trying to appeal to both sides. And he’s trying to keep the focus on Trump.

“[Biden] is trying to paint a bigger picture about what is happening in the world in this moment and how the United States is grappling with the challenges,” Blinken said. “The foundation for our success in dealing with the world is both the strength of our democracy at home and the resilience of the coalition of democracies abroad. From [Biden’s] perspective, President Trump has taken a sledgehammer to both.”

During his Thursday speech, Biden will commit to holding a “Summit of Democracies” in Washington in his first year as president, to rally democratic countries around the cause of freedom and the challenge of rising authoritarianism throughout the world. The summit would include nongovernmental organizations dedicated to the promotion of human rights and other values.

He will criticize Trump for giving Saudi Arabia a pass on the murder of Post contributing columnist Jamal Khashoggi and for embracing North Korean leader Kim Jong Un. “At the moment that the world is looking to the United States to be the leader of the free world, President Trump looks like he is working for the other team,” Blinken said.

In a nod to public weariness with seemingly endless U.S. military interventions abroad, as well as dissatisfaction because of gaps in the benefits of globalization, Biden will articulate a “foreign policy for the middle class.” He will propose broad investment in infrastructure, education, health care and green innovation to make the United States more resilient and competitive on the world stage.

“The essential part of a national security approach is that the U.S. government must focus more directly on an inclusive, domestic, economic agenda,” said Tom Donilon, who served as national security adviser during the Obama administration. "Your international and military primacy is directly related to the depth and breadth of your economic strength at home.”

Biden will again seek to thread a needle, acknowledging the need to strongly respond to the challenge of a rising China, while criticizing Trump’s approach as being too unilateral and economically counterproductive. He will point to the president as being complicit in the resurgence of nationalism, xenophobia and isolationism both at home and abroad.

Don’t expect Biden to lay out a vision for trade; that will come in a future speech. Regarding military intervention, Biden has said he wants to pull all U.S. combat troops from Afghanistan, but Blinken said Biden would leave some counterterrorism or Special Operations forces there in a noncombat role. Similarly, in Syria, Blinken added, Biden believes some specialized U.S. troops on the ground can yield huge benefits if properly leveraged.

Can Biden, in this political environment, explain to voters that he has a vision for U.S. foreign policy that centrists can love and that progressives can live with? One that defends internationalism while responding to the populists’ legitimate grievances? One that distinguishes between “forever wars” and special-operator-led troop commitments? One that commits the United States to lead a repair of the liberal world order without breaking the bank?

On foreign policy, as with other big campaign issues, Biden is running to save the system Trump has attacked, not to transform it into something new. At the same time, Biden has to convince voters he understands that much of what has changed since he left the vice presidency may never change back.

Biden is right to argue the world is better off when the United States leads nobly to address complex issues based on common values and increasingly mutual interests. But before Biden can try to repair the system Trump seems so committed to trashing, he has to convince American voters it’s worth fixing.

Read more:

Jennifer Rubin: Sanders likely can’t turn it around, but Biden can. Here’s how.

Henry Olsen: We don’t know if Trump’s foreign policy will work. But at least he’s challenging the status quo.

Katrina vanden Heuvel: The Democratic differences on foreign policy that no one’s talking about

Molly Roberts: Joe Biden is Donald Trump