WASHINGTON — The House plans to try anew next week to approve a Republican bill making it simpler for fatally ill people to try unproven treatments. And this time, the measure seems certain to pass.

Lawmakers voted for the legislation on Tuesday by a lopsided 259-140 vote. But it lost because Republican leaders had used a procedure, normally reserved for uncontroversial bills, that requires a two-thirds majority for passage. Tuesday’s vote fell just short of that.

President Trump backed the legislation and Republican lawmakers lined up behind it nearly unanimously, but Democrats opposed it by more than a 4-1 margin.

Under the measure, the Food and Drug Administration would no longer have to sign off if a doctor and a drug manufacturer agree to let a patient try a pharmaceutical that’s not been approved by the federal agency.