Mrs. Cheny wrote some book on that too if memory serves.
It is not in the presidents hands, it is in the senate hands.
I believe that you are thinking of the book that she wrote way before marriage that had some lesbian scenes described. The book was wanted by many liberals, but the publishing company told them to go pack sand (not sure if this is absolutely like this, but this is the main gist.)
You are so right about the Senate being the one's to bring it up, but the President also did make this a campaign promise and although he would not initiate it he could at least speak about it and kinda nudge the senate to get to work on the issue. Even if it does not pass at least the President would have tried that is all. We would not think him horrible if it did not pass, but that he tried.
Marriage amendment IS coming up for a vote, in Early June last I heard.