News roundup: Latest Iowa poll shows 2016 GOP field wide open, Jindal at 1% … Voter enthusiasm highest in 11 states with tight Senate races, poll says … La. Senate candidates spar in Shreveport

By the numbers: A new Bloomberg Politics/Des Moines Register Iowa Poll of likely 2016 Republican caucusgoers shows that while the party's 2012 nominee leads the pack, other established hopefuls are st…