Cornyn facing Primary challenge?

[Adlai Stevenson]

From the article about Nick Lampson considering a run against Senator John Cornyn comes this:

http://capitolannex.com/2007/04/29/tx-sen-08-lampson-getting-a-look/

What’s more interesting to me is that there are major rumblings that Cornyn is going to receive a challenge from within his own party. Names mentioned so far in that department include Lt. Governor David Dewhurst.

[AndrewTX]

The Republicans best chance to keep that seat is to not have Cornyn run again. Hopefully a good candidate will step up to the plate.

[Kevin]

Yeaaa maybe Conryn will be booted out of office.

[TheresNoMoney]

The Republicans best chance to keep that seat is to not have Cornyn run again. Hopefully a good candidate will step up to the plate.

Any Republican in the general will win this seat, Cornyn included.

[Jaggerjack]

Texas is one of the most GOP-dominated states. I seriously doubt any Democrat can take Cornyn's seat.

[adam]

I would be thrilled if Dewheart were to step in and boot that horse's ass off of the ticket. I will still be voting for whatever Democrat is put up if Cornyn remains on the ticket.

[RBH]

The Texas Republican Party hasn't had a serious primary race for a state office since 1990, at the very least

[Sam Spade]

First Question:  Why would Dewhurst risk pissing off Republican party heads by running against an incumbent he doesn't disagree with on hardly anything for a Senate seat where that incumbent has nearly $4 million in the bank, thereby putting the strong chances he has as being the successor to Rick Perry in 2010 in considerable jeopardy.

Since there really is no answer for the first, I have no follow-up.