Here is a decent look at the numbers from a blogger at the Houston paper. http://blog.chron.com/kuffsworld/2014/03/no-love-for-dan/

We saw a great example of it in 2010. Bill White received over 387,000 more votes than Democratic Lt. Governor candidate Linda Chavez-Thompson, while Rick Perry collected over 311,000 fewer votes than David Dewhurst. That’s nearly a 700,000 vote swing towards White. People often don’t realize how big the swing was towards White because the Republican tidal wave of 2010 was too big for it to matter, but in a more normal year, 700,000 votes is more than enough to make a difference.

Consider this scenario: Turnout in November is 4.9 million voters – a bit less than 2010, but more than any other off year. The average statewide Republican wins with a 57-43 margin, which I think we can agree is healthy enough to invite plenty of post-electoral scoffing at Battleground Texas and any thought of a blue state in the foreseeable future. Well, in this scenario a Bill White-sized swing is just about what it would take to tip an election, since the average vote tally would be 2.8 million to 2.1 million. If there’s any Republican candidate capable of inspiring that kind of disloyalty among his fellow Republicans, it’s Dan Patrick.

Again, it is early but Dan Patrick could alienate sufficient number of voters to swing the election towards Leticia