President Trump's refusal to take Chris Wallace's prompt to condemn white supremacy during Tuesday's debate and his "stand back and stand by" comment about the Proud Boys became the No. 1 storyline from the debate online, according to exclusive data from NewsWhip.

Why it matters: The post-debate response put Trump — not Joe Biden — on the defensive, and allowed the former vice president to dodge blowback from his own shortcomings in the debate.

By the numbers: Among the 100 most-engaged stories coming out of the debate, the 3.24 million combined interactions (likes, comments, shares) on stories about Trump's Proud Boys comments and the ensuing uproar were 34% higher than the next biggest topic: the performance of Wallace as a moderator.

The criticism of Wallace largely came from conservative media outlets, which framed the Fox News host as being biased against Trump.

• The single most-engaged story from the debate came from the Daily Wire: "Chris Wallace Faces Intense Backlash, Including From Colleagues, Over Bias During Debate" (1.12 million interactions).
• Mainstream media criticism of Wallace centered around his inability to keep the conversation from going off the rails.

Between the lines: With the guns of the conservative media ecosystem trained on Wallace, Biden received less incoming for his wobbly performance, including punting on whether he'd support adding justices to the Supreme Court and deferring on a number of Trump's direct challenges on issues like his support from law enforcement.

The biggest anti-Biden storyline of the debate was about the suspicions from the right that he was receiving extra debate assistance:

• "Trump camp seeks extra debate rule: Third party inspectors to look for electronic devices in candidates' ears" (Fox News, 454k)
• "WATCH: Wire Or 'Shirt Crease'? Something Appeared To Be Going On Under Biden's Jacket" (TrendingPolitics.com, 187k)
• "Biden Asks For Breaks Every 30 Minutes During Debate: Report" (Daily Wire, 126k)

After Wallace and 'Proud Boys', the poor quality of the debate overall was the third-biggest topic.

• In addition to stories about planned changes to future debates, highly engaged pieces included commentary about how the rest of the world reacted to the spectacle in the U.S.

Our 2020 attention trackeris based on data from NewsWhip exclusively provided to Axios as part of a project that will regularly update throughout the 2020 campaign.

See all past editions of the tracker here.