My premise is that the Republican tax pitch is self-contradictory, as it tries to have it both ways on the question of middle-class taxes.
The comromise bill, as written, tries to be long-run deficit-neutral -- allowing use of the Byrd rule to allow passage by 51 votes by offsetting huge corporate tax cuts with higher taxes on individuals, so that by 2025 half the population, and most of the middle-class, would see taxes go up. But those tax hikes are initially offset by a variety of temporary tax breaks.
Republicans are simultaneously arguing that those tax breaks won’t actually be temporary, that future Congresses will extend them. But they also need to assume that those tax breaks really will expire in order to meet their budget numbers. So the temporary tax breaks need, for political purposes, to be both alive and dead, like Schrödinger's cat.
So, either they won't be cut in the future, leaving the middle class with higher taxes OR they will be extended, leaving the nation with a massive addition to the debt -- and that debt will be used by conservatives to cut Medicare, Social Security and Medicaid.