you are thinking too much about israel/italy.
such fates can easily be avoided.
and do you really think, the official alt-right-party would have gotten as many vote as "the party not really rejecting the alt-right but not alt-right"?
No, but the center-right party would have required the alt-right party's support to govern, so in the end the result would not have been all that different.
If the alt-right party grew too large and stayed too extreme, and the Repubs didn't win a large enough percentage but still had a plurality, they would either govern in confidence-and-supply or a grand coalition.
