By Michelle Conlin and Amy Tennery
CLEVELAND (Reuters) - A defiant Ted Cruz said on Thursday he refused to be Donald Trump's "servile puppy dog," further exposing Republican rifts just as Trump seeks to unite the party and rally Americans behind his unconventional White House bid.
Cruz, the U.S. senator who came in second to Trump in the race for the Republican nomination after a bitter campaign, was booed by delegates at the party's convention in Cleveland on Wednesday night when he refused to endorse Trump in a high-profile speech.
The conservative from Texas stood his ground on Thursday, the fourth and last day of a sometimes chaotic meeting.
Republicans had made the theme for the day "Make America One Again" but Cruz's revolt underscored the tough task the candidate and the party faced as Trump prepared to close the event on a high note with a prime-time speech on Thursday evening.
With Trump set to accept the formal presidential nomination for the Nov. 8 election and officially launch his campaign against the presumptive Democratic nominee, Hillary Clinton, Republicans are still struggling to pull the party together around the New York real estate developer.
Popular with supporters for his broad slogans, off-the-cuff style and promises to apply business savvy to the economy and get tough on immigration and security, Trump has been thin on policy.
Some of his key proposals, such as imposing a temporary ban on Muslims entering the country and building a wall along the border with Mexico, have been troubling to many in the party establishment; other ideas, such as his scepticism about free trade, have been at odds with Republican orthodoxy.
Cruz, 45, who may be preparing for another run at the presidency in 2020, refused to put aside his anger at Trump's sometimes crude rhetoric.
During their primary battle, Trump insulted the senator's wife Heidi for her physical appearance and suggested that Cruz's father was linked to late President John F. Kennedy's assassin.
"I am not in the habit of supporting people who attack my wife and attack my father," Cruz told a meeting of the Texas delegation in Cleveland.
Trump aides put a positive face on the dispute and said the booing incident proved the party was in fact lined up squarely behind Trump, who has never been elected to public office and who was previously best known to Americans as the tough-talking star of reality TV show "The Apprentice."
"Other than a small group of people who have suffered massive and embarrassing losses, the party is VERY united. Great love in the arena!" Trump wrote on Twitter.
Trump, 70, said his speech would deal with such issues as trade, law and order, and border security. "I think my message is a good message. It got me here," he told ABC News.
CRUZ GETS PERSONAL
Republican candidates had pledged during the primary contests to support the party's eventual nominee. Trump accused Cruz of breaking his promise.
"That pledge was not a blanket commitment that if you go and slander and attack Heidi that I’m going to nonetheless come like a servile puppy dog and say ‘thank you very much for maligning my wife,’” Cruz said. He did say he would not vote for Clinton.
The convention has been plagued by lapses from Day One.
Some of the party's leaders stayed away, marking their disapproval for the candidate. Then Cleveland's Quicken Loans Arena briefly erupted in chaos on Monday when opponents of Trump stormed out of the room and others chanted in a failed attempt to force a vote opposing his candidacy.
Then one of the event's highlights, a speech by Trump's wife on Monday night, caused controversy over plagiarism because she used some lines that were similar to passages in an address by first lady Michelle Obama in 2008.
Comments by Trump to the New York Times raised fresh questions about his commitment to automatically defend fellow NATO members if they were attacked.
In response to a question about potential Russian aggression towards the Baltic states, Trump told the newspaper in an interview that if Moscow attacked them, he would decide whether to come to their aid only after reviewing whether those nations "have fulfilled their obligations to us."
After Trump's remarks, the White House said the United States has an "ironclad" commitment to mutual defence among the NATO allies. NATO Secretary-General Jens Stoltenberg said he would not interfere in the U.S. election campaign but added that solidarity among allies was a key value for the group.
Trump and his aides have been unable to put to rest questions about whether they can mount a sophisticated campaign to take on Clinton's well-oiled operation. He currently trails her in most opinion polls and needs the lift a candidate traditionally gets from the party convention.
Speakers in Cleveland have placed a heavy focus on defeating Clinton, rather than on policy. The audience frequently chanted "Lock her up," in a call to jail the former first lady for her use of a private email server while she was secretary of state and her handling of an attack on a diplomatic facility in Benghazi, Libya in 2012 that killed four Americans.
As the gathering headed toward what is meant to be its big closing event, some in the party were depressed about the convention and the rifts exposed by Trump's candidacy.
Annie Dickerson, an adviser to Republican megadonor Paul Singer and a delegate from New York, said, “I’ve been at these conventions since 1980. I’ve never seen it this disunited.”
Cruz, known as an ideologue of the conservative Tea Party movement who strongly favours small government, has been a controversial figure himself, upsetting fellow Republicans in Congress by plowing his own furrow.
Pro-Trump delegates were furious about his speech.
Susan Hutchison, chair of the Washington delegation to the convention, said she confronted Cruz after his address and called him a "traitor to the party."
"I always heard he didn’t have that many friends in Washington D.C. He certainly didn’t have that many friends in this room last night," Trump's son Eric told NBC's Today show.