And be careful when people use the term, "extreme". Trump is not an "extreme Republican", he's the consummate mainstream Republican since he is the leader of the party and almost his entire party supports him. Liz Cheney and Mitt Romney are the "extreme Republicans" today.
You can Ilhan Omar an "extreme Democrat" in some of her stances because she actually is way out of tune with the rest of her party, who have proven this with their votes. Biden, on the other hand, is a mainstream Democrat, and so on.
This is an interesting point. You define what is extreme in relation to the current state of opinion, so Trump will effectively be a mainstream republican.
I like working this in a different manner:
for me extremism happens when two or three of these are there:a) You are not open for a discussion on the ideas - e.g. they are God given or they are the only truth and anyone saying anything slightly different is wrong "by definition".
b) You are willing to impose those ideas, even if it means breaking the consensus, passing over large numbers of people's rights, demoting a rightful government,...
c) People opposing are no longer opponents, worthy of respect, but rather "enemies" or "infidels" or "traitors" or ...
Under this definition, Trump is not mainstream, is he?
You will notice that "extreme right" and "extreme left" are not that different, which is actually what happens in the real world out there.
But that definition of "extreme" doesn't tell you what you need to
do.
And as far as that definition goes, I'll plug in one of my "extreme" beliefs: that we should punish stealing.
a) I'm not open to discuss this. If we let thieves go unpunished, we'll have rampant crime, and I don't want that.
b) If the majority of Americans suddenly thought stealing was okay, then I would do everything I could to stop that, so..
c) Yes, I call people who think stealing is okay... all kinds of mean things
.
Obviously I'm inventing a simplified example here, but I think you get the idea.
So for me, "extreme" doesn't actually tell you anything useful, except to point out where somebody sits in the current political spectrum within their political party.
You can also try to point at "extreme" policies, which wouldn't be defined on any kind of spectrum, but rather as a measurement of the aggregate change to all Americans (in our case). For instance, Obamacare was "extreme" because it changed pretty much everybody's health care insurance in the US, and just about all Americans have heath care--and the change to people's lives was significant in many cases. On the other side are the Republican crackdowns on abortion, which is a very big change to people's lifestyles and health. You can call both of these policies "extreme" in that sense.
With that definition you can grade the two political parties, overall, by the amount of change they each will make to the country, and you can call the one that will pass bigger changes for more people a more "extreme" party. But obviously that gets into a deep partisan discussion...