WASHINGTON — Rep. Kat Cammack (R-Fla.) is calling for all congressional staff to undergo background checks and dishing on growing foreign influence campaigns that she describes as “the worst kept secret on Capitol Hill.” Cammack has introduced a resolution that would also mandate disclosure of staffers’ nationalities as well as any payments by foreign governments to current or new Capitol hill hires. The proposal comes after reports emerged last month that the FBI has been investigating a senior GOP aide for allegedly acting as a foreign agent on behalf of Qatar, as well as revelations that spies for Cuba and...