Postal inspectors and federal agents have opened an inquiry into mailings sent to election offices and congressional locations across the country, after at least some of the envelopes were found to contain an unidentified substance, according to a statement from the bureau. The correspondence arrived in the weeks before the November 3 vote.

Broadcast coverage identified the Washington offices of several U.S. senators among the locations receiving suspicious correspondence. Envelopes addressed to Senators Lisa Blunt Rochester, Alex Padilla, and Kirsten Gillibrand were among those flagged, though postal screening intercepted a portion of the items before they reached their intended recipients.

Correspondence addressed to at least six Senate offices on the Democratic side was intercepted in the majority of cases before any of the envelopes reached their intended recipients, according to reports from a television news outlet. The suite of Senate Minority Leader Schumer was listed among the locations that had been targeted.

An envelope containing an unidentified white powder arrived at the Oklahoma State Election Board on Oct. 13, prompting staff to clear the building. No injuries among staff were reported, according to Paul Ziriax, secretary of the Oklahoma State Election Board. The board indicated that elections oversight functions would remain intact despite the episode.

Postal Service investigators stopped a piece of mail containing a white powdery substance before it could be delivered to the office of Ohio Secretary of State Frank LaRose, he told reporters. According to LaRose, the Ohio matter has been placed under FBI jurisdiction.

On October 14, a piece of mail flagged as potentially suspicious by Wisconsin Elections Commission staff was left unopened pending further review. On-site screening turned up no hazardous substances, and the commission's own assessment recorded neither injuries nor adverse health outcomes among those involved.

Meagan Wolfe, who administers the Wisconsin Elections Commission, told reporters the episode would leave the office's operations unaffected. Two national bodies representing election directors and secretaries of state noted on October 14 that polling offices across the country already operate under established security protocols and contingency arrangements. A joint statement from the coalition called on those administering elections to be free from threats to their personal safety while performing official duties.

Packages deemed questionable by recipients arrived at a number of election offices during November 2023. A joint advisory from the FBI and the United States Postal Inspection Service disclosed that fentanyl was detected inside four pieces of mail directed at election officials. No sender has been named by investigators, and the total number of mailings distributed remains without official confirmation.

Voters are scheduled to head to the polls on Nov. 3 for the midterm elections, which mark the country's next nationwide contest.