Who makes the decision to appeal a case that the federal government loses?

I would assume that either the attorney who lost the case (in the case of a US Attorney) or the Attorney General would make that choice.Who makes the decision to appeal a case that the federal government loses?
I think it would be the branch of the government that lost the case. If you lose a case, you decide to appeal or not. If you sue the Federal Peanut Brittle Commission and they lose they could appeal.Who makes the decision to appeal a case that the federal government loses?
This is an interesting question. A couple of thoughts: the solicitor general will have something to say about it because an appeals case begins to establish precendent in a way a district court case does not, thus the solicitor general will only want cases appealled where the government has a good chance at prevailing. Secondly, he will balance the need to appeal with other considerations.

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