Republicans should think beyond the next 5 minutes
Republicans should not hand Democrats the opportunity to ask "Were you wrong then, or are you wrong now?"
The Indiana Secretary of State nomination race has been one of the nastiest races I have seen. It was nasty in 2022 as well, which has me thinking about Republican primaries and convention races. (Obviously, all of the advice below also applies to Democrats.)
My advice for Republicans is this: Think carefully about attacks on your opponent. If you lose, is this someone you can support in the general election against whoever the Democrats nominate? If yes, going "scorched earth" on a fellow Republican will put you in an uncomfortable position in the general election. The inevitable question will be "You said X is untrustworthy, unqualified, unreliable, of poor character and has bad polices. Yet you are enthusiastically supporting him now. Were you wrong then, or are you wrong now?"
The other danger is that, even if you support the nominee, going too negative can lead some of your supporters to not vote for your victorious opponent in the general election.
Of course, even if you win, there is a danger in going too negative. Your opponent may refuse to support you in the general election and take some of his supporters with him. If the general election is going to be close, lingering hard feelings over a bitter primary or convention battle could cost you a victory in the general election. Demanding "party unity" after you have waged a "scorched earth" campaign against a fellow Republican makes you look entitled.
Unless the other Republican really is so toxic that you cannot support him in the general election, it is wise to be restrained in your negative campaigning against him. Yes, I have said negative campaigning is often necessary, as the voters or delegates deserve to know all of the information to make an informed choice. However, a "scorched earth" campaign that ignores the implications for a general election is unwise if the nominee is someone you could support in a general election.