During a clash over health care during the Democratic debate tonight, Julian Castro questioned Joe Biden’s memory.

Castro was responding to Biden’s claims about his alliance with Barack Obama, and said, “Of course we owe a debt of gratitude to President Obama. Of course I also worked for President Obama, Vice President Biden, and I know the problem with your plan is that it leaves 10 million people uncovered.

Castro called out Biden for not telling the truth, he said he wants all Americans to have a “strong” Medicare option, but that he also supports Americans having a private plan.

“But the difference between what I support and you support is, Vice President Biden, is that you require them to opt in and I would not require them to opt in,” Castro said.

“They do not have to buy in,” Biden responded. “They do not have to buy in.”

“You just said that two minutes ago,” Castro jumped in.

As they began to argue, Castro reiterated that Biden was contradicting himself.

“Are you forgetting what you said two minutes ago?” Castro questioned as the crowd gasped and cheered.

“Are you forgetting already what you said just two minutes ago?” he asked again.

Biden huddled with Bernie Sanders as Castro continued to hammer on him.

“I’m fulfilling the legacy of Barack Obama and you’re not,” Castro lectured as Biden bristled.

“That’d be a surprise to him,” Biden chortled.