By next week, everyone will have forgotten about this story; it's only effect will have been to give political junkies something hem and haw about.
And to provide the Democrats with future talking points.
Candidates use negative campaigning primarily to throw their opponents off-message.
In The Mahabarata, the great epic war poem of Hinduism, the heroes are fighting a great battle, badly outnumbered. But their advantage is that they are so good and pure that their chariots do not even touch the ground.
At one point, the enemy's great warrior is slaughering their men by the hundreds. The only thing the warrior cares about besides killing is his beloved son, Asamthwatta. The heros hatch a plan to defeat him, by making him believe that his son has been killed.
They find an elephant named Asamthwatta and chop it's head off. At that point, they all start yelling that Asamthwatta has been killed. The hero's leader, who never told a lie, adds under his breath "Asamthwatta the Elephant". But, nevertheless, at that point, his chariot falls to the ground and sinks into the mud. He must fight the rest of the battle without his great advantage.
Of course, the enemy's hero, on hearing of the death of Asamthwatta, falls to the ground and is quickly slain. But the loss of the floating chariot is far greater than the gain of killing this one warrior. They eventually win, but at a much greater cost.
The point of the story is that Mitt Romney has been seen, by many, as being the clean technocrat who is above the fray. He has lost that presumption over this matter, and will now have to fight it out in the mud like everybody else. This is his "Asamthwatta the Elephant" moment.