He’s not asking for the citation for the quote. He’s asking for the citation of the veracity of the assertion. We know Adam Schiff said the thing. What matters is the justification for saying the thing.
With no data to justify it (and plenty available showing it’s not true), this is just further evidence Democratic leadership is stuck in the mindset of political battles from 30 years ago. If Trump were running in the political reality of the 90s with his current background and record, even current Biden would mop the floor with him. But we’re not in the age of the party of Gingrich. This is the party of Trump, and facts and record don’t matter to Trump voters and Republicans in general. Welcome to 21st century American politics, Mr. Schiff.
What I consistently don’t see brought up is the fact that the “chaotic withdrawal” was directly set up by Trump. He signed the agreement with Afghanistan that put a fixed date on the withdrawal squarely in the next President’s term. This gave enemies a clear timetable of US actions beforehand, which gave them a significant advantage. So Biden was left with the choice of either fulfilling the US promise, despite it being in every way a bad construct, and executing an extremely difficult withdrawal, or harming the US image on the global stage by reneging on an already agreed upon deal.
I would go so far as to say this, like the expiration of the middle class portion of the Trump tax cuts, was specifically designed to make the next administration, which was always very likely to be Democrat, look bad regardless of the cost or collateral damage.