The GOP can replace a vacated position due to death, declination (decline or resign), or "otherwise," but cannot initiate the process. Trump would have to quit, and the "otherwise" would require a such a long legal process to determine what "otherwise" could possibly mean, that there is no time to explore such a precedent before the election itself. And they run the real risk of damaging themselves through such a cavalier bypass of the democratic process when a party can so easily replace a candidate put there by The People. History has shown the danger of convenience and expediency for one party when it later comes back to bite them at the hands of the other; a nation of law is weakened by the attempt.
Josh Putnam, a University of Georgia lecturer and expert on the machinations of the parties said, "Let’s be clear here: The rule is intended to fill vacancies, not to lay the groundwork for a replacement."
Rule 9:
https://www.washingtonpost.com/news...blicans-to-boot-donald-trump-from-the-ballot/