The second-tier candidates are wary of trying to replicate the Hail Mary pass Ms. Harris heaved at the first debate in June. Her highly personal attack on Mr. Biden over busing won her a much-needed spike in donations and a lift in the polls, but her gains turned out to be fleeting and her broadside angered some voters uneasy with intraparty conflict.

…Senator Cory Booker also tangled with Mr. Biden in the second debate, but he has appeared to gain little from the encounter. Yet even as he continued to target the former vice president in New Hampshire — “We can’t make the mistake that says, ‘Oh, we got to play it safe,’” he warned Democrats — Mr. Booker also turned his attention to Ms. Warren.

“This election is not just about our plans, it’s about our heart and gut,” he said

The One-Two Punch That Second-Tier Democrats Are Counting On – The New York Times

Oh, Cory… Knock it off. you sound like a snipy little wannabe mean-girl.