A heated interaction between candidates at the Democratic debate on Tuesday went viral on social media, but it took until Wednesday evening for audio to illuminate what was said.

Sen. Elizabeth Warren (D-Mass.) was seen refusing to shake the hand of Sen. Bernie Sanders (I-Vt.) after the debate. Viewers on social media speculated on what appeared to be a heated disagreement between them.

On Wednesday, CNN reported that they had found backup audio of what was said during the interaction.

"I think you called me a liar on national TV," Warren said to Sanders.

"What?" Sanders replied.

"I think you called me a liar on national TV," she repeated.

"You know, let's not do it right now. If you want to have that discussion, we'll have that discussion," Sanders offered.

"Anytime," Warren responded.

"You called me a liar," Sanders fired back. "You told me — all right, let's not do it now."

The disagreement grew out of a report from CNN that four sources claimed Sanders had told Warren that he believed a woman couldn't win the presidential election. Sanders immediately denied the claims in a firm statement, but Warren later confirmed the report.

They briefly discussed the disagreement during the debate, which angered Sanders supporters on social media. After the debate, it flared up again in the heated altercation.

Here's the video of the interaction: