Vietnam’s Communist Party leader, Nguyen Phu Trong, will meet with President Obama in the Oval Office on July 7. He is an influential behind-the-scenes figure in Vietnam’s one-party leadership structure, analysts say. (Tran Van Minh/AP)

Forty years after the fall of Saigon, President Obama is seeking to reconfigure a historically difficult relationship with Vietnam into a strategic partnership against China.

In a meeting freighted with symbolism, Obama on Tuesday will welcome Vietnam’s Communist Party leader, Nguyen Phu Trong, to the White House two decades after the onetime enemy nations formally normalized relations.

Administration officials said Hanoi has been signaling interest in forging deeper economic and military ties with the United States, and Obama has extended a hand to Vietnam, which is among the 12 nations involved in an expansive Pacific Rim trade pact. And there has been considerable talk that the president is thinking about making a stop in Vietnam during a tour of Asia this fall.

The unusual nature of Trong’s visit is accentuated by the fact that Obama rarely receives foreign leaders who are not official heads of state in the Oval Office.

He played host to Vietnamese President Truong Tan Sang at the White House in 2013, and he met with Prime Minister Nguyen Tan Dung during a regional summit in Burma last fall.

Street vendors cook and sell dried seafood from their bicycle carts in District 1 in Ho Chi Minh City, Vietnam in March. (Linda Davidson/The Washington Post)

Administration officials described Trong as the most powerful person in Vietnam’s one-party leadership structure, a behind-the-scenes figure who has significant influence in political decision-making. Trong, as party chief, has traditionally been a “more conservative element” of the leadership, an administration official said.

Getting Trong’s support to move forward on the Trans-Pacific Partnership (TPP) trade accord and other U.S.-led initiatives is crucial, said the official, who was not authorized to talk on the record and so spoke on the condition of anonymity.

“Trong is a hard-liner who does not want to give away anything on the human rights side,” said Marvin Ott, an Asia scholar at the Wilson Center. “But if he can have a good visit and he and Obama have some chemistry . . . that will be a signal that the last real resistance inside the Vietnamese leadership has gone away.”

For Obama, the meeting comes as he has engaged in new diplomatic overtures to a series of longtime U.S. adversaries, including Cuba, Iran and Burma (also known as Myanmar). In late July, the president will visit Kenya and Ethi­o­pia, two other countries that have employed harsh tactics in dealing with political dissidents.

Human rights advocates criticized Obama’s willingness to receive Trong, who does not hold an official government position. More than 100 Vietnamese are imprisoned on political charges, according to the State Department, a number that has fallen by about 25 percent in recent years but remains a sticking point for U.S. diplomats in Hanoi.

“It’s a reward that is not worth the price,” said John Sifton, Asia advocacy director at Human Rights Watch. “You’re telling this regime and others, ‘Freedom or not, you will be rewarded.’ . . . The price of saber-rattling with China is that you throw human rights under the bus.”

Rep. Zoe Lofgren (Calif.), a longtime advocate for human rights reform in Vietnam, was among a Democratic congressional delegation led by House Minority Leader Nancy Pelosi (Calif.) that visited the nation in March to talk about the TPP and other issues. In a meeting with Trong, Lofgren presented him with a list of political prisoners who she said should be set free.

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“I don’t think he was very happy with our advocacy, but we didn’t go there to make him happy,” Lofgren said in an interview Monday. She said Obama needs to press Vietnam to commit to enforceable labor and human rights protections in the trade deal, and she questioned why the president is meeting with Trong in the Oval Office rather than a less-prestigious location of the White House.

State Department officials said the president will press Trong on human rights, but they emphasized that there was no promise from Vietnam to release prisoners or amend free speech laws in exchange for the meeting with Obama. By contrast, Cuba released an American last year, paving the way for the reestablishment of relations, and Burma released several dozen political prisoners before Obama’s historic visit there in 2012.

Obama restated his philosophy last week when he formally announced plans for the reopening of U.S. and Cuban embassies this month after 54 years of Cold War isolation.

“I believe that American engagement — through our embassy, our businesses and most of all, through our people — is the best way to advance our interests and support for democracy and human rights,” the president said in the Rose Garden. “Time and again, America has demonstrated that part of our leadership in the world is our capacity to change. It’s what inspires the world to reach for something better.”

Obama’s overture to Vietnam is part of a larger strategy by his administration to shift U.S. diplomatic attention away from traditional hot spots in the Middle East and Europe to meet China’s rise in Asia. The strategy got a major boost when Congress approved Obama’s request for fast-track trade promotion authority last month — legislation that could smooth the path for the TPP, which would encompass nations that together make up 40 percent of the world’s gross domestic product.

Obama has touted Vietnam and Malaysia, where last year he became the first U.S. president since Lyndon B. Johnson to visit, as among the Southeast Asian nations that have been responsive to U.S. engagement in a fast-growing region.

Over the past two years, Hanoi has become alarmed by Beijing’s maritime assertiveness in the South China Sea, a strategic shipping lane that China has sought to control. Last spring, China positioned an oil rig 120 miles off Vietnam’s coast, near islands claimed by both countries and breaching Vietnam’s exclusive 200-mile economic zone under international law.

Though Beijing withdrew the rig under international pressure last summer, Chinese authorities moved it back near Vietnam last month after plans for Trong’s visit were made public.

That move “will add a sense of urgency to Hanoi’s strategic thinking,” said Ernest Bower, a Southeast Asia expert at the Center for Strategic and International Studies. The United States and Vietnam share a view that China “cannot be allowed to override international law and define its sovereign interests based on history or the size of its military or its economy.”

Foreign policy experts caution that Hanoi will continue to do business with Beijing and will seek not to provoke China into a military confrontation. But administration officials point to the TPP trade accord as an example of a U.S.-led initiative that will help raise labor and environmental standards in Vietnam, Malaysia and other emerging economies.

In the United States, labor unions have denounced the TPP, saying it will lead to further outsourcing of American manufacturing jobs to Vietnam.

Beyond the strategic politics, there remains “a kind of residual American public curiosity about Vietnam,” Ott said. “We invested so much there; it cost us so much. But since then you’ve had a remarkable tableau of people-to-people contacts with tourists and Marines going there, and it brings something real to the impetus for normalization. In a peculiar way, there’s a real bonding going on.”