Two top congressional Democrats have asked Facebook and Twitter to investigate attempts by Russia-backed accounts to undermine Special Counsel Robert Mueller's investigation with a hashtag campaign calling for the public release of a partisan memo involved in the probe.

Why it matters: The letter from Sen. Dianne Feinstein and Rep. Adam Schiff is an attempt to draw attention to the possibility that Russian accounts boosted the "#ReleaseTheMemo" campaign. If that's true, the Democrats wrote, "we are witnessing an ongoing attack by the Russian government through Kremlin-linked social media actors directly acting to intervene and influence our democratic process."