They could take him down in the jungle primary. But that opens the door to a Democrat.
Not much likely in a statewide office like Senator. John Bel Edwards got in by fake name recognition ("Edwards") and his rep as a Navy Seal...not a combination easy to duplicate.
I see that the Republican party for the entire state of Louisiana (not just the parish of East Baton Rouge) has censured Cassidy for his vote(s).