Joe Biden, the 2020 Democratic presidential front-runner and advocate of large-scale immigration, once tried to block the evacuation of tens of thousands of South Vietnamese refugees who had helped the United States during the Vietnam War.

As a senator, the future vice president, now 76, was adamant that the U.S. had "no obligation, moral or otherwise, to evacuate foreign nationals," dismissing concerns for their safety as the North Vietnamese Army and Viet Cong swept south toward Saigon in 1975.

His position was in stark contrast to the one he took nearly 30 years later over Iraqi and Afghan interpreters who had worked with U.S. forces. "We owe these people," his then top foreign policy adviser Tony Blinken said in 2012. "We have a debt to these people. They put their lives on the line for the United States."

Biden said in 2015 that keeping Syrian refugees out of the U.S. would be a win for ISIS and tweeted in 2017 that "we must protect, support, and welcome refugees" to maintain the promise of America.

As South Vietnam collapsed at the end of the Vietnam War in the spring of 1975, President Gerald Ford and the U.S. government undertook to evacuate thousands of South Vietnamese families who had assisted the U.S. throughout the war. The leading voice in the Senate opposing this rescue effort was then-Sen. Joe Biden.

Hundreds of thousands of South Vietnamese allies were in danger of recriminations from the Communists, but Biden insisted that “the United States has no obligation to evacuate one — or 100,001 — South Vietnamese.”

In April 1975, Ford argued that, as the last American troops were removed from the country, the U.S. should evacuate the South Vietnamese who had helped the U.S. during the war, too.

“The United States has had a long tradition of opening its doors to immigrants of all countries … And we’ve always been a humanitarian nation,” Ford said. “We felt that a number of these South Vietnamese had been very loyal to the United States and deserved an opportunity to live in freedom.”

But Biden objected and called for a meeting between the president and the Senate Foreign Relations Committee to voice his objections to Ford’s funding request for these efforts. Secretary of State Henry Kissinger, who led the meeting, told the senators that “the total list of the people endangered in Vietnam is over a million” and that “the irreducible list is 174,000.”

Biden said U.S. allies should not be rescued: “We should focus on getting them [the U.S. troops] out. Getting the Vietnamese out and military aid for the GVN [South Vietnam’s government] are totally different.”

Kissinger said there were “Vietnamese to whom we have an obligation,” but Biden responded: “I will vote for any amount for getting the Americans out. I don’t want it mixed with getting the Vietnamese out.”

Ford was upset with Biden’s response, believing that failing to evacuate the South Vietnamese would be a betrayal of American values: “We opened our door to the Hungarians … Our tradition is to welcome the oppressed. I don't think these people should be treated any differently from any other people — the Hungarians, Cubans, Jews from the Soviet Union.”

The Senate Foreign Relations Committee recommended that the bill be passed by the full Senate by a vote of 14 to 3. Biden was one of just three senators on the committee who voted nay. The conference report also passed the Senate as a whole by a vote of 46-17, where Biden again voted against it.

Saigon fell on April 30, 1975, and hundreds of thousands of South Vietnamese who did not manage to escape the country were eventually sent to reeducation camps, where they were often abused, tortured, or killed.

Julia Taft, who headed the U.S.’s Inter-Agency Task Force on Indochinese Refugee Resettlement in 1975, told NPR in 2007 that the refugees should have been helped. “I mean, they'd worked with us," she said. "They'd been translators. They'd been employees. They'd been part of the South Vietnamese army, which was an ally, and just general victims of the whole chaos.”

Despite opposition from Biden, and from other leading Democrats at the time, the U.S. military evacuated over 130,000 Vietnamese refugees in the immediate wake of the collapse of South Vietnam, and hundreds of thousands more were resettled inside the U.S. in the following years.

One of those refugees was Quang Pham, who wrote a 2010 autobiography, A Sense of Duty: Our Journey from Vietnam to America, about his escape to the U.S. in 1975 at the age of 10 with his mother and his three sisters, aged 11, 6, and 2. His father, a member of the South Vietnamese military, did not make it out with them and spent over a decade in a reeducation camp before making it to the U.S. in 1992.

Speaking with the Washington Examiner, Pham praised Ford for saving Vietnamese refugees such as his family and criticized Democrats such as Biden for trying to keep them out, saying, “When we needed help, I remember who helped us — and who didn’t.”

Pham, who grew up in the U.S., joined the Marines and served in the First Gulf War, said, "The Vietnamese refugees from 1975 had a lot of help from Americans who lived near the refugee camps and from Vietnam vets who felt they had a debt to help us. And I’m grateful for that."

“When you look at the biggest supporters of Vietnam refugees, it definitely wasn’t Sen. Biden,” Pham said. “The people who wanted us weren’t necessarily who you’d expect — the openness wasn’t coming from Democrats.”

Referring to Biden, Pham said, “You have to look at foreign policy and humanitarianism. The Vietnam refugee crisis was a big deal in 1975. Even if you were against the war, why wouldn’t you support the refugees? Why wouldn’t you support the families and women and children who were trying to escape?”

“If we get involved in wars, there will be refugees ... So we need to think about our moral obligation to non-Americans, especially to our allies,” Pham said.

Asked whether he thought it was fair to judge Biden based on his actions from 1975, Pham replied, “As someone running for President, it’s part of his record, just like everything else."