It’s down to four weeks until the first votes are cast in the Iowa Caucuses. For Republican presidential candidates, the scramble is on to lock-in support. For GOP frontrunner Donald Trump, he’s on the attack. As Jeb Bush grapples with dwindling poll numbers… Trump leads the pack – accusing his biggest Iowa rival Ted Cruz of copying his immigration plan. And as President Clinton readies to hit the campaign trail…Trump is taking digs at Secretary Clinton — drudging up her husband’s past. As for other candidates, one-time high-polling Ben Carson is fading. His campaign is regrouping after three top aides resigned in one day.