It is actually non-partisan. You Republicans/Conservatives are just struggling with it because this tax plan just blows up the deficit.
"The Congressional Budget Office (CBO) is a federal agency within the legislative branch of the United States government that provides budget and economic information to Congress. Inspired by California's Legislative Analyst's Office that manages the state budget in a strictly nonpartisan fashion, the CBO was created as a nonpartisan agency by the Congressional Budget and Impoundment Control Act of 1974.
There is a consensus among economists that "the CBO has historically issued credible forecasts of the effects of both Democratic and Republican legislative proposals."
https://en.wikipedia.org/wiki/Congressional_Budget_Office