“I think I was wrong then about the path that inflation would take,” Ms. Yellen said in an interview with CNN, adding that the economy had faced unanticipated “shocks” that boosted food and energy prices.

Republican lawmakers, who have spent months blaming President Biden and Democrats for rising prices, gleefully seized upon the admission as evidence that the administration had mismanaged the economy and should not be trusted to remain in political control.

The Treasury Department has scrambled to clarify Ms. Yellen’s remarks, saying her acknowledgment that she misread inflation simply meant that she could not have foreseen developments such as the war in Ukraine, new variants of the coronavirus or lockdowns in China. After a book excerpt suggested Ms. Yellen favored a stimulus package smaller than the $1.9 trillion that Congress approved last year, the Treasury released a statement denying that she had urged more spending restraint.