In the interest of making Superman "All-American" and ensuring he has no clear political ties, a recent issue of "Superman" which focused on the presidential election took great pains to keep who Clark was voting for a secret. In fact, there's a running gag about Lois always hounding him about who he's going to vote for, and him never telling her.
I realize they were deliberately trying to make him stay sympathetic to readers of both the right and left wings, but... holy shit, man. If you can't even tell your own SPOUSE who you're voting for in the presidential election, your marriage is EFFED UP. If my wife couldn't tell me who she was going to vote for, I would think that was a clear sign of... problems.
After reading this and then also reading an online article where various webcomic authors were asked who their fictional characters would vote for, I got to wondering... "Who would the major players in the DC Comics universe vote for?"
Of course, "Major Players" is a broad definition. So let's shrink that down to focus on the most popular/well-known members of the Justice League, just to retain a narrow focus.
Superman: Despite the fact that he won't even tell LOIS who he's going to vote for, Clark is big on equality among all people, big on promoting peace in even the most heated conflicts and big on inspiring hope in others. Which means he's clearly an Obama man.
Batman: An intellectual like Bruce is going to have some severe reservations about anti-intellectual Sarah Palin. That having been said, I doubt he has much taste for Obama's plan to raise taxes on the wealthy - not because he's greedy or doesn't want to share his wealth, but because Bruce wants the allocations of his funds towards charity or towards Bat-gear to be decided on HIS TERMS, no one else's. What's more, I think he probably respects a guy that can endure torture and still come back a stronger person for it. He votes for McCain.
Wonder Woman: Diana is a powerful supporter of environmental efforts and also an avid supporter of strong, intelligent women. As such, she votes for Obama mostly to vote AGAINST Sarah Palin's presence in the White House.
Green Lantern: Well, this really depends on which one you're talking about. Hal Jordan was a military pilot; he votes for McCain because military respects military, and he can further respect the man's mediation attempts in the Senate besides, though I suspect someone that takes such pride in staying cool under fire does have some issues with McCain's temper. John Stewart also has a military background, but going farther back than that, has a background as a black kid growing up on the streets hoping and dreaming of something better. He naturally goes for Obama, despite the military tugging him towards McCain a bit. Kyle Rayner, being an artistic, younger, peacenik-type, is also an Obama sorta guy. Beyond that, do we care about the others? I think I don't.
The Flash: I'm not going to do for him what I just did for GL. Let's just focus on Wally West, since he's been the most prevalent during my lifetime. Uh... do you think Wally votes? Can he handle standing in line that long? Maybe he rushes by the polling place repeatedly all day long, looking for the shortest line every time he zooms past. Regardless, Wally's pretty liberal. Just look at this "wealthy playboy" years. I'd say he's probably pro-Obama, but I don't have the insight into his comic-based characterization that I do many of the others.