WASHINGTON (AP) — Two Republican senators unveiled a Medicare rescue plan Thursday that features an accelerated transition to private health insurance for many seniors, a gradual increase in the eligibility age, and higher premiums for middle-class and upper-income retirees.

Sens. Tom Coburn of Oklahoma and Richard Burr of North Carolina say they're not out to win a political popularity contest. Instead, they want to engage fellow policymakers and the public in a "grown-up" conversation about the scope of changes needed to preserve Medicare in some form for future generations.

"All of us in Congress are running around fixing everything except our biggest problem," Coburn said in an interview. "If you don't start fixing Medicare now, you can't save it."