Joe Biden is pretending to defend Obamacare while implicitly admitting it has failed to live up to its promises.

Yesterday, the former vice president debuted a new health care plan, which would expand subsidies in the program while creating a new government-run health insurance plan—a "public option"—that would be available inside the exchanges.

Currently, people who make up to 400 percent of the poverty line, about $48,000 for an individual or about $100,000 for a family of four, are eligible to receive subsidies for coverage purchased through the law's health insurance exchanges, insulating those people from much of the cost of coverage. Those who make more than the 400 percent threshold, however, tend to face extremely high premiums; Biden's plan would simply cap premiums at 8.5 percent of household income. The additional subsidies, as well as the implementation of the public option, would cost about $750 billion over a decade, according to his campaign—not too much less than the $940 billion Obamacare was estimated to cost over its first decade.

Biden's plan is notable mostly for its explicit rejection of Medicare for All, the single-payer plan proposed by Sen. Bernie Sanders (I–Vt.) and backed by rival candidates such as Sens. Elizabeth Warren (D–Mass.), Kamala Harris (D–Ca.), and Cory Booker (D–N.J.). The Sanders plan would eliminate virtually all private insurance in the space of just four years, forcing everyone into a single government-run insurance system. By any measure, it would be tremendously disruptive, and polls show that even if the idea of Medicare for All is popular, the elimination of private insurance is not.

It is also a defense of Medicare as it exists today, one that mirrors the tack that President Trump and other Republicans have taken against Sanders' single-payer proposal: At an AARP event last night, Biden warned that with Medicare for All, "Medicare as you know it goes away."

Biden warns the @AARP audience that under Medicare for All: "Medicare as you know it goes away. It's gone." Adds: "Dropping 300 million people on a new plan is a little risky, I think." — Alice Miranda Ollstein (@AliceOllstein) July 15, 2019

Biden is apparently betting that by campaigning against Medicare for All, and the socialist tendencies it represents within the Democratic party, he can win over moderate voters. Biden is also framing his approach as a way of preserving and building on top of Obamacare, which as vice president under President Obama, he helped usher into law.

In a video touting his plan, Biden said he was proud of his work on the health care law, calling it a success, and warning that passing Medicare for All would meaning getting "rid of Obamacare." The public option, he says, is the best way to "lower costs and cover everyone."

Given Biden's role in the passage of Obamacare, it would be difficult for him to simply run against it because to do so would be to admit that the most prominent initiative of the Obama administration—sorry, the "Obama-Biden administration"—was a failure. Biden's rivals who are running on Medicare for All, which would blow away the current system, are explicitly running on this notion.

Yet Biden's new plan essentially makes this admission anyway. Obamacare was supposed to provide coverage to those who don't have it and lower the price of health care, but for all intents and purposes, that is the same promise that Biden is now making about his plan.

Indeed, when Biden talks about building on the existing system, he sounds more than a little like Obama did when selling Obamacare: "I believe it makes more sense to build on what works and fix what doesn't, rather than try to build an entirely new system from scratch," the former president said in a 2009 speech making the case for the law. Biden is pitching an expensive overhaul of Obamacare on the promise that it would do what Obamacare was supposed to have already done. Which means that for all the feisty back-and-forth about health care policy, nearly all of the Democrats running for president appear to agree on at least one thing: Obamacare isn't working.