One reason is that Senator Kennedy and other proponents misstated the effects of the 1965 immigration act. I don't know if they intentionally lied or they just didn't know or didn't care. Back in 1965, when it was acceptable to bring up such topics, Senator Kennedy guaranteed that the immigration bill would in no way change the ethnic make of up the United States. The proponents also promised that the bill would not significantly increase immigration. But, we have more immigration in a week now than they promised would ever occur under the bill. They said to expect a few thousand immigrants during the first 3 years or so and then immigration would drop to virtually nothing. Now, if the opponents were smart, they would have insisted on putting caps in the bill rather than taking Senator Kennedy's word for it.