Feinstein also pressed former Homeland Security Secretary Jeh Johnson, who defended efforts by the Obama Administration to both warn states - and warn the public about the Russian election threat.
"Senator, the American people were told," Johnson said.
"Not sufficiently in any way, shape, or form," Feinstein replied.
Johnson acknowledged that an early October 2016 warning about Russian actions - issued both by DHS and the broader U.S. Intelligence Community - did not get the press traction that he thought it deserved, mainly due to other breaking news about the campaign for President on that day.
"It was below the fold news, the next day, because of the release of the Access Hollywood video the same day," Johnson said, referring to the tape of President Donald Trump in which he bragged about how he treated women, a revelation that roiled the 2016 campaign for the next several days.
At the hearing, Johnson did not mention what else was released on the same day - as just minutes after the Access Hollywood tape was made public, Wikileaks made the first release of hacked emails from John Podesta, a top aide to Hillary Clinton - all of that combining to overwhelm the U.S. government warning about Russian actions.
In hindsight, members of both parties said it was very obvious that - at the time - Russia was actively trying to cause trouble in the 2016 elections.
"Russian government actors scanned an estimated 21 states, and attempted to gain access to a handful of those," said Sen. Richard Burr (R-NC), the chairman of the Senate Intelligence Committee.
"In at least one case, they were successful in penetrating a voter registration database," Burr added.
Burr said his panel's investigation showed that DHS and the FBI in 2016 did alert states of the Russian threat, but in a "limited way," which resulted in most states not treating the information as an imminent threat.