Jeb Bush announces his commitment to "phase out" Medicare

Renewing Republicans' long opposition to Medicare, Jeb Bush above announced his plan to "phase out" Medicare because - he argues - it is fiscally unsustainable:

"A lot of people recognize that we need to make sure we fulfill the commitment to people that have already received the benefits, that are receiving the benefits. But that we need to figure out a way to phase out this program for others and move to a new system that allows them to have something—because they're not going to have anything."
You see?  Republicans are only acting responsibly and, as Jeb says, "the Left needs to join this conversation" to "persuade people" that Medicare is unsustainable.

Kevin Drum has the perfect response to Jeb and other Republicans:

Just yesterday we got the latest projections for Social Security and Medicare. If they're correct, the cost of both programs will top out at a combined 12 percent of GDP by the middle of the century and then flatten out. That's about 3 percent of GDP more than we're spending now.

So this is what Jeb is saying: Right now the federal government spends about 20 percent of GDP. We can't afford to increase that to 23 percent of GDP over the next 30 years. That would—what? I don't even know what the story is here. .  . .

This whole thing is ridiculous. Over the next 30 years, we need to increase spending by 1 percent of GDP per decade. That's it. That will keep Social Security and Medicare in good shape. Why is it so hard for people to get that?

Yes, that's it. One sentence.  "Over the next 30 years, we need to increase spending by 1 percent of GDP per decade."  Medicare is not bankrupt, and certainly no more so than, say, the Defense Budget.

It is inconceivable to me that Republicans could have run a presidential campaign in 2012, and now it appears in 2016, on a fake narrative to destroy Medicare when the truth is so simple.  As Drum asks, is this so hard to get?  Would the above sentence be too "wonky" for Democrats to explain consistently?

I don't think so, but the painful truth is that Democrats have failed to do that.