"But, under a 2015 Supreme Court decision, Democrats believe they may need only a simple majority to reduce tax breaks and deductions. That legal analysis, which hasn’t yet been tested in court, would apply to reducing the “pass-through” income tax break."

2/3 to make the deal, but only 50% +1 to break it.  Evidently to the Supreme Court a "deal is a deal" except when it isn't.