There are some real strategic problems for them here. They've always attracted support from the far edge of one side of the political aisle, and moving to the center only weakens them. There's no support in the middle.
I tend to disagree with this part of your post.
The fringe has proven to not provide enough suport for them. But make no
mistake, the fringe will ALWAYS support them.
They are going after the middle fence sitters now.
If they can gather enough of them... and add them to the fringe, they will get stronger.