It's kind of ironic that the vast majority of Americans with German ancestry vote Republican while that party wouldn't get 20% of the vote here. The Republican Party is pretty much seen as a joke here, even among a lot of conservatives.
It’s even more extreme with Dutch-Americans.
At the time of Dutch immigration to the US, Dutch culture was very religious and conservative, and Dutch-Americans have avoided the cultural revolution that swept over the Netherlands in the intervening decades. For instance in 1922, the vote broke down as follows
Catholic Parties: 29.86%
Protestant Parties: 25.52%
Socialist/Communist Parties: 21.21%
Classical Liberal Parties: 14.81%