President Donald Trump’s sprawling tax bill is starting to shrink in size as the strict rules of the Senate become a roadblock to some of its provisions.

Language is already being struck by the Senate parliamentarian, a nonpartisan referee on what is and is not allowed under the filibuster-skirting process of reconciliation. Core elements of the bill, a set of tax, border, and defense priorities, are expected to stay ahead of a vote next week. But some language that made it through the House has run into the Byrd Rule, which requires that all language have a direct fiscal impact.