Unfortunately (and why, big media outlets?) we still have limited polling in this race, but it looks like John Cornyn still can't break 50 percent. This is no panacea for Steve Stockman, though. Per Politico, many tea partiers think he's too nuts, or has too dark a past, or is too flighty, to replace Big John.
Wikipedia's page on the 2014 race for this seat, all primaries and the general, kind of confirms this. Dwayne Stovall has more endorsements than Stockman, and a number of local TP groups.
Can he pull a Ted Cruz and send Cornyn to a runoff?
To be honest, I doubt it.
I don't think any of Cornyn's opponents have as much gravitas with the far right as Cruz did two years ago. Second, the bigger number of contestants makes name recognition at a higher premium. Per state Rep. Kyle Kacal, I wouldn't be surprised to see a "collapse" on Cornyn for that reason alone. Third, while they don't totally like him, Cornyn still sits better with the far right than David Dewhurst did two years ago.
I wouldn't be surprised if Cornyn is held below 65 percent, but a runoff would surprise me. And, I wouldn't be surprised if a few of the far right "stay home" in November. How many, I don't know.
Update, Feb. 27: Tea party groups may be starting to coalesce behind Stovall. It may well be too late, thouugh.
That said, a brief glimpse at Democrats. If endorsements mean anything, Michael Fjetland is the odd person out. Both Mr. Pro-Life, David Alameel, and Maxey Scherr, rounding up traditional Democratic organizations despite Wendy Davis and Leticia Van de Putte stupidly, selfishly, or whateverly endorsing Alameel, are far, far ahead of F-land in endorsements. In fact, Wiki lists ONLY the Texpatriate blog as an endorser of him. Scherr has a few media endorsements. The big East Texas media outlets are showing their true colors by plugging Alameel, and without much questioning of him.