Sen. Chris Van Hollen, another progressive leader who endorsed El-Sayed, said the race “should be a wake-up call to the Washington Democratic establishment.” Mr. Thanedar lost to Donavan McKinney, a state representative, in the 13th Congressional District, which includes parts of Detroit and its suburbs. Mr. Thanedar, in contrast, has consistently voted to fund aid for the Jewish state. Mr. Thanedar was the latest pro-Israel Democrat to fall to a challenge from the left. But, of course, the Democratic primary electorate and the general election electorate are wildly different groups.