washington members u.s. house intelligence committee thursday interview head data analysis firm determine whether donald trump election campaign team seek help find thousands email miss hillary clinton private server three source familiar session say trump campaign hire alexander nix company cambridge analytica june 2016 pay 6.2 million last december accord federal election commission record month firm hire nix email wikileaks founder julian assange help track 33,000 email clinton supposedly delete private server daily beast wall street journal report october nix want convert miss potentially damage email searchable database use trump campaign pro-trump political action committee journal report wikileaks confirm reuters thursday approach nix representative say turn request intelligence committee investigate possible collusion trump campaign team russia 2016 election matter also investigate special counsel robert mueller three congressional committees russia deny meddle election trump say collusion moscow campaign representatives elijah cummings jerrold nadler top democrats house oversight judiciary committees thursday ask republican committee chairmen issue subpoena document cambridge analytica giles-parscale another data analysis firm work trump campaign spokesmen cambridge analytica giles-parscale immediately respond email request comment cummings nadler say send letter two company decline answer question whether contact foreign actors 2016 presidential campaign source say intelligence committee members meet washington law office thursday conduct interview nix skype unite state source say interview last 90 minutes cia federal bureau investigation national security agency say january russia use propaganda social media mean meddle 2016 election try help trump defeat clinton report agencies say russian intelligence service hack email document democratic national committee democratic party organizations use wikileaks release house committee question head trump campaign data firm source