Weeks before Americans vote in the midterm elections, federal investigators are tracing a wave of suspicious mail that reached election offices and congressional offices across the United States. The FBI disclosed the investigation on Thursday, October 15, 2026, and said it is working with the US Postal Inspection Service and the US Capitol Police to intercept the remaining letters and identify whoever sent them.
The episode is trending per news coverage because of its scale, its targets, and its timing. Election offices in at least 15 states reported receiving or being the intended recipients of similar mailings, and several US senators were among those targeted. No injuries have been reported, and officials have stressed that election operations are continuing. But the sheer number of letters, more than 100 by the accounts given to investigators and reporters, has made this one of the most widely discussed election-security stories of the week.
What investigators say happened
According to the FBI, a series of letters containing an unknown substance was mailed to election officials and lawmakers. The US Postal Inspection Service said some of the letters were intercepted before delivery and are now in law enforcement possession. A deputy chief inspector with the Postal Inspection Service, Brendan Donahue, told reporters that some letters contained an unknown substance and that investigators were working to respond to each incident and identify the person or people responsible. He did not confirm a total number of letters.
Other figures have circulated through officials briefed on the investigation. Three election officials briefed on the evolving inquiry told the nonprofit news outlet Votebeat that they had been told more than 100 letters were sent to people and groups across the country. Law enforcement sources cited by ABC News gave a similar preliminary figure of more than 100 letters that appeared to contain white powder. Those numbers remain preliminary, and it is not yet clear how many letters went to election offices, how many went to politicians, and how many went to other recipients. Votebeat corrected an early version of its report to make exactly that point: while more than 100 suspicious letters were sent, the breakdown by recipient type was not yet known.
The Senate Sergeant at Arms warned Senate offices that some letters could still reach their destinations despite the interception effort, and advised staff to treat suspicious mail with extreme caution. The notice reportedly noted that the letters carried multiple postage markings. The House Sergeant at Arms told House offices that district mail could be forwarded to the Capitol complex for rigorous screening. The investigation has been described as focused on the Senate, with the House monitoring the situation.
Who received the letters
The recipients named so far span both parties' institutions, though the senators publicly identified have been Democrats. Senate Minority Leader Chuck Schumer and Senators Chris Murphy, Alex Padilla, Lisa Blunt Rochester, and Kirsten Gillibrand were among those whose offices were sent letters, according to statements from their offices and reporting by ABC News, CNN, and other outlets. Most of the letters addressed to senators were intercepted by postal inspectors or Capitol Police before reaching staff.
Gillibrand said in a statement that a letter addressed to her New York City office had been intercepted by the Postal Inspection Service, and thanked postal inspectors for protecting her staff. Murphy's office said the senator and his staff were not in immediate danger thanks to safety protocols and the investigators involved. Blunt Rochester's office said a letter sent to her Dover office was intercepted by Capitol Police and taken for investigation, and that neither the senator nor her staff were in immediate danger.
Election offices were the other major group of recipients. States where offices reported receiving or having similar mailings intercepted include Delaware, Louisiana, Oklahoma, Wisconsin, Ohio, Nebraska, Washington, Pennsylvania, and Connecticut, with additional states reported by national outlets. One polling organization was also said to be on the recipient list given to officials. The full list of recipients has not been publicly released, and investigators have not said whether the sender chose targets from a single list or from several.
The Delaware evacuation
The most disruptive single incident took place in Delaware. Just after 2 p.m. on Thursday, October 15, an employee in the State Election Commissioner's Office of the Delaware Department of Elections opened an envelope that was later found to contain a white powdery substance. The department said staff followed security and Postal Service instructions: the envelope was isolated, staff members were decontaminated and evacuated, and the heating and ventilation system was shut down. State and federal law enforcement were called in, and the FBI took over the Delaware investigation.
Out of an abundance of caution, all election offices statewide sent their nonessential state employees home that afternoon. The commissioner's office was temporarily relocated to the Kent County office in Dover, and the department said public meetings, absentee ballot processing, and election testing were proceeding as planned. Early voting in Delaware was scheduled to begin Thursday, October 22. The building that housed the commissioner's office was closed while the investigation continued.
Similar disruptions were reported elsewhere. Packages containing powdery substances led to evacuations in Louisiana and Oklahoma. In other states, letters were intercepted before they could be opened. The pattern, investigators say, is consistent with a single coordinated mailing rather than a series of unrelated incidents, although that has not been formally confirmed.
What testing has found so far
The central unanswered question in the first days of the investigation was whether the powder was actually hazardous. The answer so far is reassuring but incomplete. The Wisconsin Elections Commission said it received a suspicious mail piece containing an unidentified powdery substance and that after a thorough examination the item was deemed not dangerous. Wisconsin's chief election official, Meagan Wolfe, said the incident would not affect the general election and that election officials were prepared to handle many challenges.
Separately, sources cited by NBC News said preliminary testing found the contents were not hazardous, while additional laboratory testing was continuing. That distinction matters. A preliminary field test can rule out some threats quickly, but full laboratory analysis takes longer and is needed before investigators can say with confidence what the substance was. Until that work is finished, officials are treating every unopened letter as potentially hazardous, which is why the interception effort and the warnings to staff remain in place.
No injuries have been reported in connection with any of the letters. That includes Delaware, where the envelope was opened, and the states where evacuations took place. Officials have not reported any illness among postal workers, election staff, or congressional aides linked to the mailings.
Why the timing matters
The letters arrived less than three weeks before the November 3 midterm elections, which will determine control of Congress and decide a long list of state and local races. The midterm campaign is already in its final stretch, with early voting under way or about to begin in many states and millions of mail ballots in circulation.
That is part of why the story has drawn so much attention. Election offices are the places that receive, process, and count ballots, and any threat against them raises questions about continuity even when the immediate danger turns out to be low. The Postal Service said earlier in October that it would take extraordinary measures for the 2026 election, including extended hours at some retail locations and expedited handling, extra deliveries, and special pickups of ballots. The suspicious mailings arrived on top of that already complex operation.
Election-administration groups moved quickly to frame the incident as an attack on the people who run elections rather than on any particular result. The National Association of Secretaries of State and the National Association of State Election Directors said in a joint statement that those who administer elections should never fear for their safety while carrying out their essential duties, and that any threat or attack on an election official is unacceptable. The Postal Inspection Service used similar language, saying it was committed to protecting the nation's election officials from threatening and dangerous mail.
A precedent from 2023
This is not the first time US election offices have been targeted with white-powder mailings. In 2023, election offices in six states received letters containing white powder, including some with traces of fentanyl. That episode led to evacuations, hazmat responses, and a federal investigation, and it became a reference point for election officials when the new wave began.
The comparison is useful but limited. In 2023, the mailings were spread over a longer period and the confirmed hazardous content, fentanyl traces in some letters, gave investigators a concrete lead on the substance involved. In the current case, the scale appears larger, more than 100 letters against a smaller number in 2023, but the preliminary testing so far has not found hazardous material. Investigators have not said whether the two episodes are connected, and there is no public evidence of a link. The main lesson officials drew from 2023 was procedural: treat every suspicious item as dangerous until cleared, isolate it, and let specialists handle it.
A separate case not to confuse with this one
Readers following election news this week may also have seen a separate federal legal action involving California's voter rolls. On October 15, the Justice Department sued the State of California, alleging that more than 20,000 people who are likely noncitizens are registered to vote there, and asking a court to order the state to set aside mail ballots from flagged voters until citizenship could be verified. California officials disputed the claims.
That lawsuit is a separate matter from the suspicious-letters investigation. There is no public evidence linking the two, and they involve different agencies, different legal questions, and different facts. The lawsuit turns on voter-list data and ballot-counting rules; the letters investigation turns on who mailed physical envelopes and what they contained. Treating them as one story would mislead readers about both. Voter-roll disputes have also surfaced in other countries this month, but each dispute turns on its own country's laws and records.
What to do if you receive suspicious mail
Officials have repeated the same basic guidance for anyone who encounters a suspicious letter or package. Do not open it further, do not shake, sniff, taste, or touch the contents, and do not try to clean anything up. Put the item down gently, leave the area, and keep other people away from it. Wash your hands with soap and water if you handled it, and call 911 or local law enforcement. If you are at work, tell a supervisor and follow your workplace's security plan. Postal inspectors and the FBI have asked that suspected items be preserved for investigators rather than thrown away, because the envelope, the postmark, and the contents can all carry evidence.
Warning signs that should raise caution include an unexpected letter from an unknown sender, excessive postage or odd postmark patterns, a lumpy or rigid envelope, oily stains or discoloration, a strange odor, or a handwritten or threatening message. No single one of these signs proves a letter is dangerous, and most unusual mail is harmless. But officials say the combination of an unexpected powdery substance and a threatening context is enough to stop, isolate, and call for help.
What happens next
Three tracks will decide how this story develops. The first is the laboratory work: full analysis of the intercepted letters should establish what the substance was and whether any of the letters contained anything hazardous. The second is the sender investigation: postal markings, fingerprints, DNA, purchase records, and surveillance footage are the usual tools in a mail case, and investigators have not said how far along they are. The third is the protective track: continued interception of letters still in the mail system, screening of congressional and election-office mail, and guidance to staff in the run-up to Election Day.
Officials have also been careful about what they have not claimed. No suspect has been publicly named, no motive has been established, and no link has been drawn to any political group or foreign actor. Early reporting that more than 100 letters were sent came from officials briefed on the investigation rather than from a published FBI count, and the FBI itself has not confirmed a total. Those gaps are normal in the first days of a federal mail investigation, but they mean the picture could change as testing and interviews proceed.
For now, the practical message from officials is steady. Election offices are operating, ballot processing is continuing, and the investigation is active. The letters have not stopped the election, and no one has been hurt. What they have done is put election workers, postal inspectors, and Capitol Police on high alert at exactly the moment when the country's election machinery is under the most strain. The next updates are likely to come from the FBI, the Postal Inspection Service, or the state election offices that received the letters, and the key facts to watch are the lab results, any suspect identification, and whether additional letters surface. Election security procedures built for exactly this kind of disruption are being tested in real time.
Sources: FBI and US Postal Inspection Service statements; Reuters; Associated Press via ABC News; CNN; NBC News; Votebeat; Delaware Department of Elections (per news coverage, 15-16 October 2026).