The Republican Party holds round five in its series of president ial debates tonight. This one in las vegas. Donald trump will be front and center with ben carson on his right and ted cruz on his left. New Jersey Governor Chris Christie was a late add. A Des Moines Register poll of likely iowa ccus goers shows cruz leading by ten points with just seven weeks to go before the caucuses. Nancy cordes reports. Reporter this is the second poll in less than a week to show cruz leading the gop field in iowa. The Trump Campaign trashed the poll, while trump himself chose to trash cruz, saying hes unfit for the job. I dont think hes qualified to be president. Reporter donald trump had this message for gop leaders who might think his support in awhat is waning. I dont go down, i go up. Im going to win. Reporter and he went after his sometimes ally ted cruz after promising for weeks he wouldnt. You look how hes dealt with the senate where he goes in there like a maniac. Reporter on twitter, cruz