The Catholic Church's Amendment to Ban All Non-Catholic Marriages . . .

If the Catholic Church is going to be consistent, why the focus on gay marriage?  Shouldn't it be fighting, preaching and lobbying just as strongly against all forms of marriage that do not meet its definition of "sacramental marriage"?  Why isn't the church pushing for a constitutional amendment banning all weddings that are not performed by a Catholic priest, and all marriages that are not between Catholic, non-divorced couples (or whatever else the church laws require)?  In the Catholic Church's eyes, aren't all non-sacramental marriages (i.e., all non-Catholic marriages) just as much a threat as gay marriage?