Vice President Mike Pence was one short plane ride away from shaking hands with an alleged interstate drug dealer. Pence abruptly canceled his trip to Manchester, N.H., earlier this month but never said why he was pulled from Air Force Two at the last minute. The vice president’s aides and even President Donald Trump himself kept up the suspense. “You'll know in about two weeks,” Trump told reporters at the time. “There was a very interesting problem that they had in New Hampshire.” Among the problems was a federal law enforcement probe involving individuals Pence would likely encounter, according to...