Four Democrat US Senators issued aletter to the manufacturers of US voting machines, urging them to explain why they are selling devices with security flaws, that if exploited, might undermine the results of the 2020 elections. The companies, ES&S, Dominion Voting, and Hart InterCivic have more than 90% of the US election equipment market share and previous studies have proven their machines' vulnerability. The companies have until 9 April to respond to the senators' letter.