In another blow to the Republicans’ tax and spending cut bill, the Senate parliamentarian has advised that a proposal to shift some food stamps costs from the federal government to states — a centerpiece of GOP savings efforts — would violate the chamber’s rules.

The cost-share plan was a critical way for Republicans to trim spending to pay for their massive reconciliation package and farm bill programs.

The ruling by the parliamentarian sent G.O.P. lawmakers back to the drawing board to cover the costs of President Trump’s domestic policy bill.