US Republican presidential candidate Donald Trump has veered deep into controversial insult territory. Reuters

Republican presidential candidate Donald Trump raised the stakes in what he proudly considers his fearless stance against "politically correctness" by slamming rival Ted Cruz as a "pussy" – effectively saying Cruz was as weak as a woman.

Trump tried not to completely "own" the pejorative against Cruz. He attributed it to a woman in the crowd at a campaign rally, saying he was quoting her, then laughingly chastised her for using the word, reported The Hill.

"She just said a terrible thing," Trump pointed out in a pretend-scold at an arena in Manchester, New Hampshire before asking her to raise her voice. "You know what she said? Shout it out, 'cause I don't want to," he continued. "OK, you're not allowed to say — and I never expect to hear that from you again — she said: 'He's a pussy.' That's terrible."

The crowd erupted into laughter then began chanting: "Trump! Trump! Trump!"

"What kind of people do I have here?" he said, to laughter. He then recalled getting flak for not condemning supporters who said offensive things about President Barack Obama. "The press got very angry because I didn't defend the president, and I didn't reprimand the person who said it. So, I just want to tell you, ma'am, you're reprimanded, ok?"

He added with a smile: "For the press, this is a serious reprimand."

The Mother Jones news site said the comment "crossed a new line in American politics".

The insult came as Trump was attempting to underscore what he sees as Cruz's weakness on the issue of national defence.

Trump referred to the last debate when he vowed to get tough on Middle Eastern terrorists, even urging some torture worse than waterboarding. Trump said he was surprised Cruz didn't agree with him.

A spokesman for Cruz's campaign tweeted that Trump was "turning the campaign into the latest episode of a reality show".

Policy.Mic claims it caught up with the woman who originally made the comment, a 52-year-old woman from Salem, New Hamsphire, whose name the online publication didn't reveal. She called herself a "huge Trump supporter," and said Cruz "doesn't have the balls to stand up to stand up to other leaders."

Trump was recently brought task for use of the P-word by journalist Tucker Carlson, who said that 15 years ago he made fun of the real estate mogul's hair. He said Trump called him on the phone, saying, "It's true you have better hair than I do but I get more pussy than you do."

Trump also went after Marco Rubio during the rally for "sweating like a dog" at the last debate.

Trump is on top of the polls in New Hampshire heading into the primary after taking second place to Cruz in Iowa.