The hardest thing about picking a presidential candidate is that you can't test them first. You can't see how they'd actually handle real presidential duties, like attempting to balance the federal budget, representing the citizenry abroad and punching out Venezuelan troops before dropping grenades in their tanks. Thankfully, you'll get the chance to see how presidential candidate Barack Obama and VP nominee Sarah Palin will stack up as they'll soon be added as DLC to Mercenaries 2. You can see the video right after the break.
Why no John McCain, you ask? Man, you don't need a video game to help you imagine what John McCain would be like as a war hero! McCain doesn't call blowing up an attacking helicopter with a rocket launcher an adventure ... he calls it "Tuesday."
When you put yourself into the public spotlight willingly (even sometimes not willingly) then you become a public figure and citizens get rights to do these sorts of things to your image.
As long as its not in the realm of libel or slander (and even then its a fine line) or some kind of copyright infringement, then you're fine. This is what South Park does, even though they've been legally attacked by many people for the libel or slander mentioned above.
It's like halloween shops selling presidential masks, or like someone above said, like south park, or like when SNL spoofed Palin. SNL IS AN ENTERTAINMENT PRODUCT. They both profit off people's likenesses, but it's perfectly legal to spoof a public figure.