Speaker Nancy Pelosi said the Trump administration would “be entering a grave new chapter of lawlessness” if it failed to turn over a related whistle-blower complaint by Thursday. (Read her letter.)

The allegations involve whether Mr. Trump pressured Ukraine’s newly elected leader, Volodymyr Zelensky, to hurt Mr. Biden’s election bid, possibly using U.S. military aid as leverage. The former Soviet republic has been fighting Russian-backed separatists, and the Trump administration temporarily withheld $250 million from Ukraine this summer.

Background: Mr. Trump has accused Mr. Biden of using his position as vice president to help a Ukrainian energy company in 2016 that was paying his son Hunter. There has been no evidence that the former vice president intentionally tried to help his son.

The Daily: Today’s episode is about the controversy.

Seeking a cyber silver bullet

Senior U.S. officials have told The Times that a cyberstrike has become the most appealing response to punish Iran, which the Trump administration has said is responsible for an attack this month on Saudi oil facilities.