If coming out in support for marriage equality costs the President the election, his recent statement will have ACTUALLY UNDERMINED PROGRESS ON LGBT RIGHTS IN THE LONG TERM! Since Romney seems willing to bend to the will of the bigots in his party, his administration could potentially roll back all of the progress made during the Obama Administration and who knows how far they will go.
Every person who believes in marriage equality and is inspired by Obama's leadership on this issue has to redouble their efforts to get him reelected to cancel out all the bigots out there that will vote for Romney now. Otherwise, even being on the right side of history isn't worth a whole lot if those on the wrong side of history get to impose their will on everybody.