The headline of the post by Carolyn Classen in B4AZ pretty much says it all. Classen cites the League's reasoning.
... This Proposition has terms which the League cannot support. The Executive Branch has indicated that this is a “take it or leave it” deal. Therefore, The League of Women Voters of Arizona has taken a position in opposition to Proposition 123. Further, the League of Women Voters of Arizona stands for democracy and we agree with Winston Churchill whosaid,“.. .it is the people who control the Government not the Government the people.” We believe this attempt to force the voters to overturn a law they lawfully enacted by refusing to enforce it and forcing them to pass another proposition in its place disenfranchises them. Therefore, the League will ask the US Department of Justice to investigate this disenfranchisement.”