Those who have been beseeching the individual states, as well as the federal government, to proclaim English as the nation's official language are not just, or even mainly, for English. They are against Spanish.
Congress made it clear in the Voting Rights Act of 1975 that the purpose of printing ballots in Spanish was to ensure that Spanish-speaking citizens were able to exercise the franchise. Eliminating these ballots would effectively disenfranchise them. Similarly, the purpose of bilingual education is to teach English while educating students in the other necessary subjects so they don't fall behind. Abolishing such programs would be counterproductive.
As for the notion that the newest generation of immigrants isn't learning English, the fact is that 98 percent of American residents over 4 years of age speak English well. In Los Angeles alone, the waiting list for courses in English for adults as a second language has over 40,000 names.