Depends on what you mean by cross the aisle, the size of the Republican Party is growing and several people have crossed the aisle to become Republicans that used to be Democrats. I think growing the party is crossing the aisle.
Clearly based on the last 12 years of Republican is far more likely to cross the aisle and work with a Democrat and vice versa. There’s pretty compelling evidence for that.
It’s not so much that the Republican Party has moved away from its roots as the democratic party has substantially moved away from its roots.
Donald Trump has most assuredly grown the party
And you keep using the phrase fanatical, which personally I think you do intentionally, but more than 50% of the nation supports Trump at this point and before Reagan second term, he was actually not very popular.
I think you do yourself a disservice to try and describe 50% of the nation is fanatical in any way shape or form