Bernie Sanders had the highest volume of Twitter mentions in the second round of the Democratic debates last week, and the debates generated 18% more tweets than the first round in June even though the TV audience was much smaller, according to data provided to Axios by Sprout Social.

Why it matters: Compared to the first round, last week's debates were heavier on disagreement and confrontation, allowing voters to see discrepancies in the candidates and how they responded to challenges in real time, a departure from rehearsed stump speeches.

By the numbers: 15 of the 19 candidates had more mentions during the second debate than the first. (Eric Swalwell dropped out of the race after the first debate, while Steve Bullock joined the stage for the second round.)

There were 1.97 million tweets about the candidates during the second round of debates vs. 1.67M in June.

tweets about the candidates during the second round of debates vs. in June. Those tweets generated 1.49M interactions last week vs. 1.41M in June.

Winners:

Sanders was mentioned more than any other candidate during last week's debates.

His biggest moments were his impassioned defenses of Medicare for All, including responding to Rep. Tim Ryan's doubts about what is covered in the plan: "I do know it. I wrote the damn bill!"

Elizabeth Warren has been mentioned more than any other candidate in aggregate for the two debates.

Andrew Yang has been hanging around the bottom end of the top tier of candidates in polling, but he nearly doubled his mentions in last week's debate — 4th-most of any candidate.

Interest in Marianne Williamson on social media continues to outpace her polling by a big margin.

Losers:

Julián Castro, one of the risers in June's debates, was less visible and saw his mentions drop by a third.

Beto O'Rourke's numbers dipped from the previous debate, and his place in these rankings (11) lags well behind his polling (6, per Real Clear Politics).

Between the lines: Yang got more of his mentions from voters 18-24 (31%) than any other candidate, while Amy Klobuchar (36%) had the highest proportion from older tweeters (55+).