Are All Politics Extreme?
I think that your question makes sense if you believe Condorcet's conjecture: that all human beings "are" the same. As soon as we add a few more variables, the question blurs. Suppose Plato's hypothesis: in every society there are three castes. The sages have as their goal the preservation of the state (that is, their good and that of others). Guardians are meant to preserve their caste at the expense of the peasants. And each peasant thinks only of himself. They are not interested in the good of the State, nor in the other peasants.
A party is like a bus. There are people who go up and down continuously. According to Condorcet, the population of the bus is always the same. Plato adds some more complexity. The critical mass of a party depends on the ruling caste: sages, guardians or peasants. The Republican Party of the Trump era is a bus full of peasants. However, that does not define the Republican Party. The Democratic Party of the 1930s was a busload of wise men. Roosevelt politics was to the left of Bernie Sanders: "He put tens of millions of people to work through “alphabetical agencies” such as the Civilian Conservation Corps, the National Industrial Recovery Act, and the Works Progress Administration. He imposed FDIC requirements on banks and insured investor’ deposits. He separated commercial banking from investment banking and created unemployment insurance and Social Security."
I think your question makes sense as long as it doesn't deviate from Condorcet's speech.