Several Democrats in Congress, including House Speaker Nancy Pelosi (Calif.) and Sen Minority Leader Chuck Schumer (N.Y.) last week asked FBI Director Christopher Wray to brief all House members and senators on foreign efforts to interfere in the upcoming national elections.

“We are gravely concerned, in particular, that Congress appears to be the target of a concerted foreign interference campaign, which seeks to launder and amplify disinformation in order to influence congressional activity, public debate, and the presidential election in November,” says the July 13 letter, which was also signed by House Intelligence Committee Chairman Adam Schiff (Calif.) and Mark Warner (Va.), ranking member on the Senate Intelligence Committee.

The four Democrats are requesting a classified defensive counterintelligence briefing that is based on “all-source intelligence information and analysis.” They want the briefing prior to the August congressional recess.

The brief letter was addressed to Wray and was also sent to Director of National Intelligence John Ratcliffe, CIA Director Gina Haspel, and National Security Agency Director Gen. Paul Nakasone.

Russian intelligence agencies interfered in the 2016 U.S. presidential election to hurt Hilary Clinton, the Democratic presidential candidate, and bolster Donald Trump’s chances to get elected, the intelligence community found.

Joe Biden, the presumptive Democratic nominee to challenge Trump in November, said last week that China, Russia and other foreign adversaries are making efforts to undermine the upcoming elections based on intelligence briefings he has begun to receive.