here's julianna goldman. >> reporter: with national security concerns rising, donald trump leads the republican pack. retired neurosurgeon ben carson is slipping. and senators ted cruz and marco rubio are gaining ground. >> i'm leading every poll by a lot. it's not even a little bit anymore. >> reporter: in the wake of the paris attacks, at least 2/3 of republican voters in the three early contests say a candidate must agree with them on how to handle isis in order to get their vote. and overwhelming majorities favor sending u.s. ground troops to the middle east to fight the terrorist group. today trump built on his controversial policy resume waterboarding, create a watch list for refugees, and monitor mosques. >> i think waterboarding is peanuts compared to what they do to us. >> reporter: in another new poll, 25% of new hampshire primary voters say trump is best equipped to handle the u.s. response to isis. rubio lags behind with 13%. >> what happened in paris could happen here. >> reporter: the florida senator said his campaign was using the issue for its first campaign ad. >> i