Democrats opposed Vietnamese refugees because they feared they would support Republicans

Washington Examiner:

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.”
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California governor Jerry Brown also opposed bringing in the Vietnamese.  Those refugees have been good US citizens.  Democrats did not want them because the Democrats were largely responsible for creating the situation that led these people to have to flee.