From what I can see, if one candidate does not receive >50% in a primary, there is a runoff between the top two candidates. Because there are only two candidates in a runoff, one will get more than 50% of the vote.
And, of course, in the November election, it’s just the person with the most votes who wins. If McDaniel runs a write-in race, he could potentially win the Senate seat with less than 50% of the vote, as long as he had the most votes of all the candidates.
Write in votes aren’t counted per Mississippi code unless it’s a replacement candidate.
And independent candidates must present by March 1.
Title 23, Chapter 15, Article 13, Part B of the Mississippi Code