If they had been able to get Graham to pull his support for Goss, the Rats would have been able to rush to the media and proclaim, "Senator Graham has worked with Goss for years and years, and he's a senator from Goss' home state, so if Bob Graham has doubts I have to consider that" and yada yada yada. They would have been able to get a lot more than 17 to vote against the confirmation then - in fact, they would have easily gotten more than 40 and thus would have been able to filibuster.
My guess is they'll pursue Plan B - watch Goss like a hawk, and the instant he does or says something they don't like, pounce on it and try to make it into a scandal so they can demand his resignation.