A Gallup survey gives Romney a 24-point lead among veterans. Obama has a slight 4-point lead among non-veterans. The two are tied when it comes to all registered voters.
The numbers become even more pronounced when you break then down among gender. Romney has a 28-point lead among male veterans, while Obama has a 5-point lead with women that have military experience.

Veterans in the U.S. today are mostly male and two-thirds are aged 50 or older. In a population that is currently evenly split in its preferences for Barack Obama or Mitt Romney for president, veterans stand out for their 24-point preference for Romney. About a fourth of men are veterans, and it is their strong skew toward Romney that essentially creates the GOP candidate's leading position among men today. Among nonveteran men, Obama and Romney are essentially tied.
Barring unforeseen developments such as the re-institution of the military draft, the proportion of the male population in this country that will have served in the armed forces will decrease in the years ahead as the older population dominated by veterans dies off. These data suggest that Democrats could get an overall boost from this demographic phenomenon as these apparently reliable Republican voters become a smaller and smaller proportion of the population.

