Data obtained by The Associated Press shows Postal Service districts across the nation are missing the agency’s own standards for on-time delivery as millions of Americans prepare to vote by mail. The lag times are especially pronounced in key regions of some battleground states, where delivery times are below the national average. That raises the possibility that scores of mailed ballots could miss deadlines for reaching local election offices if voters wait too long. Missing a deadline is one of the key reasons mail-in ballots get rejected. Postal service leaders have said the agency will prioritize election mail.