There's a lot of americans that have bad blood with the space program; deaths in a colonization program would just fuel them.
I'm pretty sure the number of deaths doesn't matter either. Only a few people died in the boston bombings and that didn't stop the entire country from turning upside down over it for a few weeks.
That's why I think that China, given time, might be in a better position for Mars colonization. Democracy is afraid of bold moves in space, while the Chinese regime will see it as a long-term chance to bolster it's position in the eyes of common people.
The willingness for a ordinary Chinese man to see his sons die in car crashes, wars or terraformed planets is exactly the same as it is for any other ordinary father anywhere else and anywhen.
Just because governments may be willing to advance on a wave of bodies, does not make it something the population will tolerate, or for long.
I'm pretty sure the number of deaths doesn't matter either. Only a few people died in the boston bombings and that didn't stop the entire country from turning upside down over it for a few weeks.