Medicare is the fastest-growing part of the federal budget aside from interest payments — a problem that has only been made worse by declining revenues under the GOP tax law.

The big picture: Spending is expected to grow by 117% over the next decade due to rising health care costs and an aging population. There’s no sense of urgency in Washington about this. And even if there was, this political environment sinks any chance of massive problem-solving.

Why it matters: The Medicare trust fund runs dry by 2026 if Congress doesn't pass benefit cuts.

• While that just means that there won’t be money to fill in the gap between Medicare spending and tax revenue paying for it, the gap only gets worse after that.

What they’re saying: “Lawmakers have their head in the sand,” said Marc Goldwein of the Committee for a Responsible Federal Budget. “For the most part, nobody wants to touch this.”

Go deeper: What happens when Medicare goes broke.