In his letter, the vice president suggested an immediate resumption of comprehensive talks, including about Iran’s nuclear program.

© Tierney L. Cross for The New York Times

The White House has been rocked by turnover and anxiety over the midterms. The president, who is tightening his inner circle, has lashed out at critics, held meandering rallies and feasted on a diet of news clips and “A.I. slop,” as one aide put it.

© Doug Mills/The New York Times