I think TN has become sort of Illinois in reverse over the last decade. Both used to be competitive two-party states (TN became winnable for the GOP in the 1920s and stood apart from the other "solid south" RAT states), but following Al Gore's embarrassing loss in 2000, the TN RAT party has really imploded and become a shadow of its former self. They had the Governorship from 2003-2010 only because RINO turd Sundquist poisoned the well for any Republican to succeed him, but the Dems lost that during the 2010 sweeps. They've failed over the last decade to win any other major office in the state, and seem to have simply stopped trying after 2008 or so. The last time was when they blew their wad with idealistic southern RAT candidate Harold Ford Jr. (folksy, uniter, black dude who appeals to whites.... this guy was the media's Barack Obama before they discovered Barack Obama!) and he lost to a sub-par GOP candidate.
Now the TN RAT party has become an non-threat at the statewide level and both they and the TN GOP know it. Of course they still have pockets in the state where Dems are successful and in power (urban areas like Memphis), but it's now a one-party GOP state at the statewide level. Even if there was another RAT presidential candidate in the future who was "competitive" in the south (Bill Clinton type moderate southern RAT), they probably wouldn't waste any resources in the formerly competitive states of TN and WV. Both have moved sharply into the GOP column in only 12 years.
Illinois is the reverse, if the state party does get involved and waste time and money putting up a sacrificial lamb, it serves no purpose. Look at what happened in 2008 when the state party laughably insisted that unknown clueless doofus Steve Sauerberg was the "only credible candidate" against Durbin, and used heavy handed tactics to make SURE he won the primary. The guy did worse than Alan Keyes in November! (of course, with the combine in Illinois, many would say that was the point and a bunch of GOP insiders struck a deal with Durbin to give him an "opponent" he could safely ignore)
I'm not sure if I buy that the RAT candidate is actually the "more conservative" choice in November, as others have noted, Corker isn't on the level of an Olympia Snowe or Mark Kirk style RINO, he's just a worthless squish. You do occasionally see flukes where the RAT candidate is more conservative though, I've seen two times where it happened in Illinois. 1998, with southern IL RAT Glenn Poshard vs. uber-RINO George Ryan (even we didn't know how bad Ryan would turn out to be back then though), and I think Judy Biggert had a more conservative RAT opponent (pro-life and pro-gun) a few election cycles back.
Was Biggert’s Democrat opponent from a few cycles ago really more conservative than her? (Biggert is pro-abortion, but she’s pro-gun, and isn’t bad on economic issues.) I find it hard to believe that a conservative could win a Democrat primary in the close-in Chicago suburbs.
Was Biggert’s Democrat opponent from a few cycles ago really more conservative than her? (Biggert is pro-abortion, but she’s pro-gun, and isn’t bad on economic issues.) I find it hard to believe that a conservative could win a Democrat primary in the close-in Chicago suburbs.