The very expression used: 'radical' infers that there's something not right with extremism. Whether it be radical right (ultra conservative, turn back the clock to 1850) or radical left (go back to the heights of the Bolshevist Revolution) there is always something wrong with political extremists. That is why the vast majority of people fall somewhere between the two.
Despite the cycnism, most people are pretty shrewd judges of how they like to see their country being run. If it is being run really badly, there are big (and I mean big, not 'rent a crowd') demonstrations in the streets like, for example, the world-wide protests against the War in Vietnam in the late 1960s early 70s.
Of course, a nation's people need remain vigilant, and not timid in coming forward if they see extremism beginning to take over - in any form - for as we know, in America and in all truly democratic countries for that matter, it's government of the people, by the people, for the people, which will provide the most freedom.