Concerns included investigation of Christie 's travel expenditures while Plouffe attorney . Biden vs. Clinton . Revelation included in new book by reporters on presidential campaign , `` Campaigns voters last year in gubernatorial reelection bid . Book also says Obama campaign conducted focus groups , polling about replacing Clinton with Biden .
Concerns included investigation of Christie 's travel expenditures while Plouffe attorney . Revelation included in new book by reporters on presidential campaign , `` Campaigns voters last year in gubernatorial reelection bid . Book also says Obama campaign conducted focus groups , polling about replacing Clinton with Biden .