The Senate parliamentarian has advised a Medicaid provider tax overhaul central to President Donald Trump's tax cut and spending bill doesn't adhere to procedural rules.

Many Republican senators dismissed the idea of overruling the Senate parliamentarian after she rejected key Medicaid provisions in Trump's tax and immigration bill Thursday, which dealt a blow to Republicans' plan to slash costs in the budget package.

The nonpartisan Senate official whose office determines if legislation fits within the rules of the chamber dealt Senate Republicans a blow on proposed changes to Medicaid.