(CNN) Donald Trump called Ted Cruz a liar on Tuesday, charging that the Texas senator repeatedly misrepresents the Republican front-runner's views.
"He's just saying lie after lie. It's not becoming," Trump told George Stephanopoulos on ABC's "Good Morning America."
"He really does lie. He's so nervous," Trump added. "I saw him the other day. He is so nervous. He is such a mess. His polls have gone down. People realize that he probably can't even run for president. He was born in Canada."
Trump's searing attack on Cruz continued a narrative he began Monday afternoon with CNN's Wolf Blitzer. Trump blasted Cruz as a "nasty person" in the interview with Blitzer and said, "Ted cannot get along with anybody."
Poll: Trump dominates GOP field
Trump and Cruz are locked in a tight battle for Iowa, which holds its first-in-the-nation caucuses on Monday. Trump has recently edged ahead of the Texas senator after days of relentless, multi-pronged attacks on Cruz.
On Tuesday, Trump took aim at a new Cruz ad that features old video footage of Trump saying he supports abortion rights.
Trump cited the ad as the latest example of Cruz misrepresenting his positions.
"I'm pro-life -- 100%. He knows it. Everybody knows it," Trump said.
The ad also shows Trump at a rally appearing to call Iowans "stupid." Trump responded on "Good Morning America" that he was simply referring to Iowans -- and Americans as a whole - who were supporting candidates other than himself.