They were opposed by the GOPe whose candidates were well funded. These folks had little money. Did it with grass roots support. Dewhurst had all the big donors on his side - the Lt Governor has great power (Governor is really a figure head in TX) to set the legislative agenda. The money people knew if he won without their support, they wouldn’t get anything through the legislature.
See #9. And all credit to them for their victories. If they can now keep it together for the General, and the GOPe should swallow their pride and give money to help them.