The Irish became "part of the establishment" through lib politics, the Italians and Portuguese brought with them corrupt politics of their homelands, the Poles became hardcore trade unionists. Let's alsonot forget about the good Scandanavian Evangelicals in Minnesota. :-)
Of course, with more wealth and assimilation, many of the descendents of those settlers became selfish yuppies and soccer moms.
Over in the Detroit area a few years back, some POS ran for office. He didn't campaign, since those that met him hated him. His name was O'Hara. He almost won.
In a non-partisan race, I'd have a good chance to win on my last name alone. In a partisan race, I think my last name would swing the vote as much as the gun issue.