Jason  Leopold reports for BuzzFeed News on two Democratic U.S. senators’ concerns about the Obama administration‘s lackluster response to Russian efforts to influence the 2016 election.

A week before the 2016 presidential election, Senators Dianne Feinstein and Benjamin Cardin sent President Barack Obama a letter urging him to take swift action against Russia for meddling in the electoral process through state-sponsored cyberattacks “on United States’ democratic institutions.”

“Such attacks cannot be tolerated and the United States must take immediate measures to ensure that those responsible are held to account,” the Democratic lawmakers wrote in a previously undisclosed letter dated Nov. 1, 2016.

“The seminal event in a functioning democracy is an election, and the international implications of the results of the U.S. election are far reaching. Russia’s actions threaten to undermine our process,” Feinstein and Cardin wrote. “Our electoral infrastructure is strong, but it is incumbent upon us to ensure that our institutions are protected. A cyberattack on our electoral process or any part of our critical political, economic or military infrastructure is a hostile action that must be countered.”

The letter was obtained by BuzzFeed News and Ryan Shapiro, a PhD candidate at MIT and the co-founder of the transparency project, Operation 45, in response to a Freedom of Information Act (FOIA) lawsuit we filed last year against multiple agencies for documents about Russia’s interference in the election. It stands as a missing piece to a timeline about Democratic efforts to encourage the White House to speak out about Russia’s intrusion sooner.

Feinstein and Cardin’s two-page letter was a dire warning to Obama. They had hoped he would immediately retaliate against Russia.