Republicans in Congress brought Democratic presidential candidate Robert F. Kennedy Jr. to Capitol Hill Thursday to help them amplify one of their core political messages: They have been victimized by a conspiracy between shadowy forces in the government and Big Tech. Kennedy, the son of Robert F. Kennedy and the nephew of President John F. Kennedy, had long been a critic of vaccines before the COVID-19 vaccine was developed. Democratic presidential candidate Robert F. Kennedy Jr. arrives to testify at a hearing of the House Subcommittee on the Weaponization of the Federal Government. (Jonathan Ernst/Reuters) But during the coronavirus pandemic...