Since our mission was to keep the stalemate between North Vietnam and South Vietnam with only preventing the North from taking over the South. We accomplished that under Nixon with the Paris Peace Accords. South Vietnam lost after we left the democrats took over the House and Senate majority and voted to cut funding to the South, and drive Nixon out of office. After this North Vietnam violated the Paris Peace Accords and at this time the democrats blocked Ford from sending any possible assistance to the South. Which resulted in a North Vietnam victory.
Regardless of how many republicans voted to cut funding the democrats had the House and Senate at the time. I just hate it how liberals blame the US military for losing as if our military was not strong enough.
Read more: Would it be right to say the US won the Vietnam War but South Vietnam lost?