DONALD Trump is under pressure to steady his Republican convention after a chaotic start which saw a plagiarism charge and other unforced errors threaten to overshadow efforts by the party to unify behind him.
However, barring last-minute complications, the unorthodox billionaire will end the night as the Republican Party's official White House nominee.
This week's four-day convention is Mr Trump's highest-profile opportunity to convince voters that he is better suited for the presidency than Democrat Hillary Clinton.
But the rocky start raised fresh questions about his oversight of his campaign, which gives voters a window into how a candidate might handle the pressures of the presidency.
The plagiarism accusations centred on Monday night's well-received speech by Mr Trump's wife, Melania.
Two passages - each 30 words or longer - matched a 2008 Democratic convention address by Michelle Obama nearly word-for-word.
Mr Trump's campaign managed to keep the controversy alive on day two of the convention by insisting there was no evidence of plagiarism, while offering no explanation for how the strikingly similar passages appeared in Mrs Trump's address.
The matter consumed news coverage from Cleveland, obscuring Mrs Trump's broader efforts to portray her husband's softer side.
Democrat Hillary Clinton pounced on the row, saying the Republican gathering had so far been "surreal", comparing it to the classic fantasy film Wizard of Oz.
"When you pull back the curtain, it was just Donald Trump with nothing to offer to the American people," Mrs Clinton said during a speech in Las Vegas.
Top Trump adviser Paul Manafort said the matter had been "totally blown out of proportion".
"They're not even sentences. They're literally phrases. I was impressed somebody did their homework to think that that could be possibly done," he said.
Republican leaders hoping to leave Cleveland with a strong show of party unity also found themselves answering unwelcome questions. Republican National Committee Chairman Reince Priebus said he "probably" would have sacked his own speech writers under similar circumstances and acknowledged the matter was a distraction.
Mr Manafort also affected Republicans' unity message by slamming Ohio governor John Kasich in his home state. He called Mr Kasich "petulant" and "embarrassing" for not endorsing Mr Trump or attending the convention, drawing quick condemnation from other party leaders worried about angering the popular governor of one of the most important election states.
It is unclear whether the controversy would have any bearing on how voters view Mr Trump, given the business tycoon has survived numerous politically perilous moments that might have doomed other candidates.
The centrepiece of the second day's programme will be the roll call vote making Mr Trump's nomination official - a once-unthinkable scenario for Republicans who spent months dismissing the real estate mogul as a mere sideshow.
Typically in both parties, the roll call is heavy with ceremonial flourishes, good cheer and mentions of the virtues of each state. This time, it is also another opportunity for discord to be heard.
Dissident delegates from several states plan to insist on abstaining or backing other candidates, according to Regina Thomson of Colorado, a leader of a group calling itself Free the Delegates.
Meanwhile, police broke up a couple of skirmishes between groups of demonstrators a few blocks from the Republican National Convention.
There was no immediate word on any arrests or injuries.
A scuffle broke out when conspiracy theorist and radio show host Alex Jones started speaking in Public Square. Police on bicycles pushed back a surging crowd, and Mr Jones was whisked away.
Minutes later, more officers on bicycles formed a line between an organisation supporting the Communist Party and a conservative religious group.
The crowds and the police presence were some of the largest and most raucous gatherings in Cleveland since the convention got under way on Monday.
