Irish-Americans are hard to pin down: Irish-American identity is very symbolic at this point. There isn't much that distinguishes Irish-Americans from WASPs outside of religious identity. At this point, there's a lot of overlap between both groups. There aren't many "pure" Irish-Americans in the US. It's easier to pin down the voting behavior of German-Americans than Irish-Americans because there are many, many communities in the Midwest which have retained many German traditions and sensibilities. German Catholics, in particular, have maintained their ethnic traditions and this is reflected in their voting patterns. They're very "swingy".
Oh, If only...