Senate Parliamentarian Alan Frumin late Monday ruled against a Republican challenge to the health care reconciliation package, a Senate aide confirmed.

Senate Republicans Monday afternoon argued to Frumin that a provision of the reconciliation package approved by the House violated Section 310g of the Budget Act. Had Frumin ruled in the Republicans’ favor, the bill would have been stripped of its reconciliation status.

Frumin heard arguments from Democratic and GOP Senate staff, and he ultimately ruled in favor of the Democrats. The Republicans argued that a provision dealing with the excise tax on “Cadillac” insurance plans impacted Social Security. The Budget Act does not permit reconciliation legislation to affect Social Security.

However, Senate Republicans remain confident that Frumin will rule in their favor on at least one of the many challenges they plan to raise.

“One down, many more to go,” a GOP aide said Monday evening.