CLEVELAND (REUTERS)- Republican presidential nominee Donald Trump will try to restore order to his convention on Thursday (July 21) with a prime-time speech after rival Ted Cruz drew boos for refusing to endorse him.
Trump's speech will close out a four-day conclave in Cleveland that exposed continuing divisions among Republicans over their nominee at a time when they need to unite for a looming battle against Democrat Hillary Clinton in the run-up to the Nov 8 election.
Those divisions were laid bare when Trump's last major challenger for the nomination, US Senator Cruz of Texas, urged Republicans to "vote your conscience" and pointedly did not endorse Trump.
Jeers erupted from Trump supporters in the crowd, and Cruz's wife, Heidi, was escorted out by security amid the shouting. "I just think it was an awful performance," New Jersey Governor Chris Christie, a close Trump adviser who was also a presidential rival, told MSNBC.
Cruz's speech was another stumble at a convention marked by several missteps, including a speech by Trump's wife, Melania, that included lines similar to those in a 2008 Democratic convention speech by President Barack Obama's wife, Michelle.
Republicans have used their convention to rally loyalists, but fissures have persisted after a brutal primary battle in which Trump defeated 16 rivals.
As the last speaker in a four-day marathon of events in Cleveland, Trump has his biggest chance yet to try to end the bickering among various factions of the Republican Party and foster a spirit of unity.
The 70-year-old New York businessman will use his speech to formally accept the Republican presidential nomination.
On Wednesday night, he emerged in the convention hall while Cruz was still speaking, a move that appeared intended to steal some attention away from the senator.
Then Trump appeared on stage with his vice presidential running mate, Indiana Governor Mike Pence, to greet Pence, who had just delivered an enthusiastic speech in honour of the nominee. An awkward air kiss punctuated their embrace.
"Trump's acceptance speech will be a worldwide event and set up the terms of the debate for the race against Clinton," said Republican strategist Scott Reed. "Nothing rallies the Republicans like a race against the Clintons and an Obama third term." Republicans have characterised a Clinton victory as a virtual third term for Obama.
The speech represents Trump's best chance yet to try to broaden his appeal. He has attracted millions of voters by pledging to toughen US immigration laws and renegotiate international trade agreements.
He needs a post-convention bounce in public opinion polls to remain competitive with Clinton, who will be in the spotlight next week in Philadelphia for the Democratic National Convention.
"It's going to be a really important speech because it's part of the reintroduction of Donald Trump," said Lanhee Chen, a Hoover Institution scholar and former aide to 2012 nominee Mitt Romney.
"This is his chance to tell in his own words why he wants to be president, why he believes he is qualified to be president and what he plans to do if he is elected," Chen said. "And those are all things that we don't have a great sense about beyond platitudes about 'making America great again.'"