Congressional Republicans are advancing a provision in a broader federal spending bill that would place new caps on how much graduate, medical and law students can borrow through government loan programs. The measure would abolish the Graduate PLUS program, which currently allows students to finance the full cost of attendance after other aid is exhausted, and replace it with a lower ceiling on federal borrowing. Students needing additional funds would have to seek private loans or other financing. Higher-education advocates warn the changes could make advanced degrees unaffordable for lower-income and under-represented students, potentially narrowing the pipeline of professionals in high-cost fields such as medicine and law. The proposal is expected to face debate when lawmakers return from the July 4 recess.