The FBI says a suspicious package addressed to New Jersey Democratic senator Cory Booker has been recovered in Florida and is similar in appearance to others received in the last few days.
It is the 11th package to be recovered this week.
Others have been intended for people including former president Barack Obama, Hillary Clinton, ex-attorney general Eric Holder, philanthropist George Soros, former vice president Joe Biden and Democratic representative Maxine Waters.
The FBI is doing a nationwide manhunt for whoever is sending the pipe bomb packages.
Officials are trying to determine if the sender was trying to sow fear or actually cause physical destruction.