U.S. Republican presidential candidate Ted Cruz  in Twitter war with Trump

Donald Trump launched a full-blown attack on Republican arch-rival Ted Cruz on Wednesday, accusing him of stealing victory in Iowa.

But  the Texas senator hit back, in a more blistering fashion, rubbishing the mogul’s presidential credentials and questioning his sanity.

“I wake up every day and laugh at the latest thing Donald has tweeted. Because he’s losing it,” said Cruz. “We need a commander in chief, not a twitterer in chief,” said Cruz on a campaign trail in New Hampshire.

“We need someone with judgment and the temperament to keep this country safe. I don’t know anyone who would be comfortable with someone who behaves this way having his finger on the button, ” he added.

The fighting began on Twitter with Trump, runner up in Iowa  lashing  out and  telling his six million followers that the evangelical conservative had only won the first vote of the 2016 election by fraud.

“Ted Cruz didn’t win Iowa, he stole it. That is why all of the polls were so wrong and why he got far more votes than anticipated. Bad!” Trump wrote.

Cruz fired back a salvo several hours later. “Yet another #Trumpertantrum… @realDonaldTrump very angry w/the people of Iowa. They actually looked at his record,” he wrote on his Twitter account.

Trump slammed Cruz for putting out a statement from Iowa saying that a fellow candidate, retired neurosurgeon Ben Carson, was quitting the race, and “lying” to thousands of voters about Trump’s policies.

Donald Trump: accuses Cruz of stealing Iowa

“Based on the fraud committed by Senator Ted Cruz during the Iowa Caucus, either a new election should take place or Cruz results nullified,” Trump wrote.

On the campaign trail in New Hampshire, Cruz looked to capitalize on his momentum against the New York billionaire, who leads Republican polls in the Granite State.

Trump has run a media blitzkrieg campaign, dishing out insults against his political rivals, Mexicans, women and Muslims, sucking the television air time away from every other candidate in the race.

But his Iowa tally — in second place at just above 24 percent, marginally ahead of Senator Marco Rubio — in the first vote raises serious questions about whether showmanship has a winning strategy.

A second hiccup, at the New Hampshire primary next Tuesday, would spell political disaster for the reality television star.

Cruz won 27.7 percent of the vote in the Republican caucus in Iowa, staking his claim to be the new standard bearer of the right.

Rubio, whose star has risen in recent weeks, took more than 23 percent, anointing him as the Republican establishment candidate of choice best placed to defeat presumed Democratic nominee Hillary Clinton.