But honestly, a binary choice is just no way to express political opinion: Why should my views on abortion correlated with my views on free trade?
At least getting a multi-party system would be worth a try.
Scanning your comment history, it looks like you're German?
I think you may have a rather badly skewed (or outdated) view of American politics. Unless you're considered quite far right by European standards, the current US Republican party's views are probably far removed from your own. Your comment about "internalizing the externalities" by raising gas taxes alone would get you skinned alive at Republican gatherings in most states. And if you view Democrats as "left", all I can say is they often make your center-right parties look like socialists.
eru's statement was "If I was living in the US, I'd probably vote mostly Republican". In the context of the discussion, I interpret that, quite reasonably I think, as broad agreement with what he perceived to be Republican policies.
My response was intended simply to point out to him that it is highly unlikely he truly has such broad agreement with Republicans, particularly in the context of other statements, and in the (hidden) context of other Europeans I've encountered who thought they would be Republicans in the US, and were quite surprised when they learned the modern state of the Republican party, which is far outside mainstream European politics.