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Julián Castro went straight for the jugular during Thursday night's Democratic debate, telling former Vice President Joe Biden that when it comes to health care, "I'm fulfilling the legacy of Barack Obama, and you're not."

Castro told Biden that his health care plan would leave 10 million people without coverage, while he wants "every single American family to have a strong Medicare plan available. If they choose to hold on to strong, solid private health insurance I believe they should be able to do that, but the difference between what I support and what you support, Vice President Biden, is that you require them to opt-in, and I would not require them to opt-in." He added, "Barack Obama's vision was not to leave 10 million people uncovered. He wanted every single person in this country covered. My plan would do that, your plan would not."

Biden interjected, saying people would not have to buy-in under his plan. "Are you forgetting what you said two minutes ago?" Castro shot back, a line that earned "oooohs" from the audience. "If you lose your job, for instance, his health care plan would not automatically enroll you, you would have to opt in," Castro continued. "That's the big difference — I'm fulfilling the legacy of Barack Obama and you're not." In response, Biden muttered, "That'll be a surprise to him." Cue more "oooohs."

It appears as though it's actually Castro who forgot what happened two minutes ago, several Twitter fact-checkers said. Julie Rover, chief Washington correspondent for Kaiser Health News, tweeted that Biden's plan would actually "auto-enroll everyone under 138 percent of poverty — the population currently eligible for the Medicaid expansion in states that have adopted it."

The Daily Beast's Sam Stein also backed Biden's version of events, saying that he "re-watched the segments where Biden talked health care and it seems pretty clear to me that Castro is, well, wrong. He never said opt-in. He said that if people lose their jobs they can automatically buy into Medicare." Stein later tweeted a follow-up, revealing that "In fact, Biden at one point said the opposite: 'Anyone who can't afford it gets automatically enrolled in the Medicare-type option we have.'"