A leading Senate Democrat sent letters to the CEOs of Facebook, Twitter and Google on Tuesday pressing them to uphold their own platform rules and take action against misinformation and disinformation ahead of the election. “I write today to again urge you to implement strong accountability and transparency standards in the context of our nation’s election,” wrote Sen. Mark Warner in the letters, adding that Google\n \n (GOOG) and Facebook\n \n (FB) remain “a vector for disinformation, viral misinformation, and voter suppression efforts.” The letters put additional pressure on the Big Tech platforms weeks before what experts warn will be a chaotic election, in which the final outcome may not be known for days or weeks. During that time, malicious actors could seek to exploit the uncertainty and sow discord among Americans by making false or misleading claims. The tech companies have announced a slew of new policies anticipating those tactics. Facebook, for example, has said it will temporarily restrict political ads one week before Election Day and will take action against candidates or parties that make premature claims of victory. Google has said it will reject all ads related to the election beginning after Election Day. Despite those policies, concerns remain about the companies’ ability to enforce them. On Tuesday, it took hours for Facebook and Twitter\n \n (TWTR) to act against false and misleading claims by President Donald Trump that the coronavirus is less deadly than the flu. Facebook removed Trump’s post, while Twitter\n \n (TWTR) applied a contextual label to his tweet. Warner, however, blasted labeling as an ineffective half measure in his letters to Twitter and Google. “It is evident that labeling has been wholly inadequate in either slowing the dissemination of deceptive content or properly contextualizing it for the majority of users,” he wrote to Twitter. Warner praised the companies for taking some voluntary steps to adopt policies proposed in the Honest Ads Act, a bill he co-sponsored along with its author, Sen. Amy Klobuchar, and 30 other lawmakers. The bill would apply the same requirements on digital political advertisements that exist for TV and radio political ads, and would require political advertisers to identify themselves. Tech companies have moved to enhance transparency with portals that allow users to see political ads and who paid for them. But, Warner wrote, it is not enough. “I also request that you more aggressively identify, label, and remove manipulated or synthetic media ahead of the election to prevent the amplification of disinformation from Russia and those following their playbook,” he said.