My question is, why do people always bring up the fact that Obama is doing this for elections only? Why would he need to do this? If the decision is between Obama or a GOP candidate on this issue alone, most people would know which would fit their beliefs on this issue the best by now. It isn't like it is a secret until election time.
I personally think that Obama is right on this issue, mostly (one of the few I agree with him, to a point, with). The only part I really don't agree on, will most likely have to be decided by the SCOTUS, and that is what a state's right to discriminate against same sex couples should be.
But this issue won't come down to Obama, since anything done to change the current policy to allow same sex couples to be recognized as legally married by the federal government will almost certainly be approved by Obama. Now, that being said, it is quite possible that a GOP candidate who gets into office will be an issue, since if such a bill gets through Congress after the election (which is plausible, considering it is still in committee) and Obama isn't in office, it is quite likely that any of the GOP candidates currently vying for the Presidency are likely to veto the bill. This would be a huge blow to equality in marriage.
So, just looking at this issue in relation to the election, an intelligent person could see that as long as Obama holds his current stance, he has the vote of those who are pro-SSM if it comes down to this issue for them, and likely doesn't have the vote of those who are pro-DOMA. He doesn't have to try to change anything at all, because his current stance of not vetoing any bills to repeal DOMA is going to be better than the GOPs candidates' position of most likely vetoing any such bill and possibly pushing for an anti-SSM amendment.