Almost everyone, it seems, has been told which Florida voter registration systems were breached during the 2016 presidential election — except for the voters whose information was targeted.

Elected leaders in Washington and Tallahassee want to tell them, but they say they can’t. The F.B.I. has kept the information classified, refusing to publicly identify the two counties where Russian hackers had access to voter data that could have allowed them to wreak havoc for voters on Election Day.

On Thursday, the F.B.I. faced a torrent of bipartisan fury from Republican and Democratic lawmakers in Florida, who, one after another, denounced the federal agency’s lack of transparency, calling it unacceptable that it has taken three years for the authorities to reveal to them which counties were hacked.

“I don’t know who the hell they think they are to not share that information with us,” Representative Matt Gaetz, a Republican from the Panhandle, said in a news conference on Thursday after the Florida delegation met behind closed doors in the Capitol with officials from the F.B.I. and the Homeland Security Department.