Vice President Joe Biden will face Congressman Paul Ryan on the debate stage tonight in Kentucky, and Paul Ryan’s Medicare plan is sure to be a hot topic.

Frank Newport, editor-in-chief at Gallup, says if Ryan doesn’t broach the subject, Biden almost surely will, “all of the polling shows that when you ask Americans flat-out whether they would like to change the system — the Medicare system — to one that includes vouchers…it’s opposed.”

Though vouchers may not be a popular solution, most independent studies of the Medicare system show that the program is not sustainable and will require reform at some point. In a recent Kaiser Family Foundation poll, “61 percent [of Americans] said, ‘hey, the system is working well now’,” cites Newport, “but 72 percent said it’s going to need changes to viable in the future.”

Ryan will likely tap into this sentiment in his discussion of Medicare and challenge Biden on his and President Obama’s policy solutions.