In order to pay for his social welfare bill, President Biden plans to crack down on tax cheats. He thinks this will save about $300 billion, but the Congressional Budget Office is expected to disagree, scoring it in the neighborhood of $200 billion. If this happens, it means that the bill would increase the deficit and Democrats would need to cut back on spending to return it to deficit neutrality.
Lefties are crying foul over this, pointing out that Republicans increased the deficit by $1.9 trillion when they passed their 2017 tax bill. Where was the CBO then?
This is a misunderstanding. In 2017 Republicans wrote a $1.5 trillion deficit directly into the reconciliation instructions. The CBO then scored their bill at $1.9 trillion, but Republicans ignored the CBO and produced their own estimates after jiggling around some of the details of the tax cut. Then they passed the bill. They did this because they never really cared about deficits in the first place.
So can't Democrats do the same thing? Sure, except that they do care about deficits. Or, to be more precise, Joe Manchin cares about deficits. Legally, Democrats can produce their own estimate of the bill's impact on the deficit, but it doesn't matter. It won't pass unless Manchin is on board.
So the CBO score is only important if Manchin thinks it is. Which apparently he does. That's it. That's the only reason the CBO score matters.