growing as iowa nears. 2012 iowa caucus winner, rick santorum, mocking filibustering in a new tv ad. >> i do not like green eggs and ham, i do not like them, sam i am. >> you want someone to read one hell of a bedtime story, ted cruz is your guy. if you want to protect america and defeat isis, rick santorum's your president. >> reporter: while rubio takes his own backhanded shots. >> words and political stunts cannot ensure our security. isis cannot be filibustered. >> reporter: the battle for the establishment crowd growing more pinched as both rubio and chris christie sharpen their tone to cast themselves as the serious alternatives to trump. >> these times and these challenges demand a grown-up. showtime is over, everybody. we are not electing an entertainer in chief. >> now, not everything in that donald trump ad is exactly how it appears. remember those images of people surging across the border? in fact, those are from morocco.