Put on your thinking cap. Here's a short version of how the Texas Democratic nominating process works. The party rules are 11 pages long.

A total of 126 delegates will be awarded based on the outcome of the vote in each of the 31 state senatorial districts.

But the number of delegates available in each district is not equal: Delegates are allocated based on the votes cast in districts in the 2004 and 2006 presidential and gubernatorial elections.

In the heavily urban, African-American districts of state Sens. Rodney Ellis of Houston and Royce West of Dallas, a good voter turnout in the past two elections means a combined total of 13 delegates are at stake in the two districts on Election Day.

Obama nationally has been winning eight out of 10 black voters, according to network exit polls.

But in the heavily Hispanic districts of state Sens. Juan Hinojosa of McAllen and Eddie Lucio Jr. of Brownsville, election turnout was low, and a combined total of seven delegates are at stake.

Clinton has been taking six of 10 Hispanic votes nationally.

So, a big South Texas win might not mean as much for Clinton as a big win for Obama in the two black districts.