New data show the number of ballots rejected for late postmarks has soared in the vote-by-mail states of Washington and Oregon. The figures highlight concerns about recent changes in U.S. Postal Service operations ahead of this fall’s pivotal general election, especially in the roughly half-dozen states that vote entirely or mostly by mail. The struggling agency has been consolidating its operations, emphasizing regional hubs in an effort to save billions of dollars. Some U.S. senators and election officials have warned that the changes could delay the application of postmarks and prevent otherwise valid ballots from being counted. They say that prediction is being borne out.