Anxious liberals have held their fire as Vice President Kamala Harris tacks to the center, but recent calls from some allies that she part ways with a popular, progressive financial regulator if she wins the White House have sparked warnings from her party's left flank of a potential "out and out brawl."

For many in the progressive movement, the question of whether to keep Federal Trade Commission Chair Lina Khan represents a pivotal question about the party’s future.