The question for voters in Tuesday's Texas runoff isn't whether a Republican will likely succeed Kay Bailey Hutchison in the U.S. Senate, but what kind of Republican?
The answer figures to reverberate far beyond the Lone Star State.
It's a primary that represents one of the nation's most vivid contrasts between the GOP establishment and the tea party. Lt. Gov. David Dewhurst faces a major threat from former Texas Solicitor General Ted Cruz.
Two months after Dewhurst's decisive win in a nine-candidate primary signaled he might coast to victory, the battle is now considered too close to call.
Cruz blocked Dewhurst from the majority he needed to avert a runoff, and his insurgent candidacy has been buoyed since by money and influence from conservative groups in and outside of Texas.