New Obama video highlighting the differences between the candidates on civil rights for gays:
You could say that before yesterday, the candidate's positions on gay marriage were about the same (and RNC chair Priebus did try to make that argument). You could say that, but if you did say that, you would be entirely wrong. Even before yesterday, President Obama refused to enforce the Defense of Marriage Act, while Romney pledges to fully enforce it. President Obama has consistently supported civil unions (even Bush supported civil unions, as the video shows), while Romney opposes them if they are equivalent to marriage.
Most egregiously, Governor Romney supports amending the Constitution to prevent states that already allow gay marriage, or might do so in the future, from extending that right to their citizens. Those who support such an amendment must give up any pretense of favoring states' rights, and should stop pretending that they want to reduce the power of the federal government. Supporters of a federal marriage amendment are just fine with increasing federal power, and are against leaving these questions up to the states, so long as the federal government denies the rights of states to decide who should or should not be allowed to marry.