Overall, Romney carried White Catholics, as did Bush and McCain. Source
Romney's vote among White Catholics in the Northeast was only 2 percentage points less than his vote among White Protestants in that part of the country. Source
Race and geography and degree of religiosity are more important than religious denomination in determining voting patterns.
Some people here just need somebody to blame (i.e. Catholics), though. One or two have even become famous (at least around here) for that.
It isn't white American Catholics colonizing America, it is Catholics from more pure, Roman Catholic nations.
Hispanics comprise 71 percent of Catholic population growth since 1960, according to the U.S. Conference of Catholic Bishops.