This kind of thing has happened for years in Republican primaries for the House in the Midwest and CA, particularly. Conservatives cannot agree on one candidate, they splinter their vote, and the "moderate" gets the nomination. I'm sure it will happen in TN too. I've notice more and more southern conservatives cannot control Republican primaries in their own region. A lot of this is merely the lack of knowledge about the candidates.
Number #1 problem = NO runoffs. Start requiring candidates to receive 50% or they go to a runoff and this cancer of RINOs winning primaries will be dramatically curtailed.
BTW, if you take note of Georgia, McKinney came in 1st place in her primary, and were it not for their requiring a runoff, she would not be in jeopardy of losing her seat.
They used to require 50%+ wins in the GENERAL, otherwise Paul Coverdell would not have won in '92 when he narrowly trailed incumbent Sen. Wyche Fowler, but conversely, GA would've had a GOP Governor as long ago as 1966 with Bo Callaway, who placed first in the general, but only with a plurality.