Hispanic Growth Shapes 2012 Race - WSJ.com
Here are two numbers that ought to worry Republicans: 56% and 64%.
Those numbers are, respectively, the percentage of America's population growth in the last decade that came from Hispanics, and the percentage of Hispanics who voted for Democrats last year.
Here is the number that ought to worry Democrats: 69%.
That is the percentage of eligible Hispanic voters who didn't show up to vote in 2010's midterm elections.
This picture—of a big and growing Hispanic population, friendly to Democrats yet still a sleeping giant in electoral terms—explains much of the activity you are seeing in early rounds of the 2012 political cycle.