Isabella Casillas Guzman, President Biden’s choice to run the Small Business Administration, inherited a portfolio of nearly $1 trillion in emergency aid and an agency plagued by controversy when she took over in March. She has been sprinting from crisis to crisis ever since.Some new programs have been mired in delays and glitches, while the S.B.A.’s best-known pandemic relief effort, the Paycheck Protection Program, nearly ran out of money for its loans this month, confusing lenders and stranding millions of borrowers. Angry business owners have deluged the agency with criticism and complaints.Now, it’s Ms. …
