I'm aware of some opposition towards Reagan from party leadership. This doesn't even being to compare. The opposition to Trump is not coming from the RNC leadership, which has folded and joined the Trump train, but from very many separate voices of influential Republican pundits, think tank experts, journalists and elected officials who are all proclaiming Trump to be a clear and present danger to the US and the world. There was nothing whatsoever on such a scale during Reagan's campaign.