CLEVELAND, United States (AFP) — The Republican convention kicks off Monday with a one-two punch of law-and-order tough-talk, and Donald Trump’s wife playing character witness as the bombastic mogul seeks to lock up his presidential nomination.

Melania Trump, a Slovenian-born former model, will headline the opening night of the 2016 convention in Cleveland, Ohio, which takes place against a backdrop of fear over racial violence and unrest abroad.

A spate of race-tinged shootings — including the killing of three police officers in Louisiana Sunday — has put the country on edge.

Terror attacks overseas, most recently in Nice, and an attempted coup in Turkey, have only stoked a sense that the world is falling apart.

President Barack Obama has urged Americans to temper their words and show stronger common resolve, but Trump is instead highlighting divisions.  

“We are TRYING to fight ISIS, and now our own people are killing our police,” Trump tweeted shortly after the Baton Rogue shooting, referring to the Islamic State group.

“Our country is divided and out of control. The world is watching.”

Trump has portrayed himself as a sheriff who can fix things.

He believes that the presumptive Democratic nominee Hillary Clinton should be jailed for using a private email server to handle sensitive government documents, something the FBI said was careless but not a criminal.

On Monday Trump will also call on retired Lieutenant General Michael Flynn and tough-talking Senator Joni Ernst as convention speakers to back up his point.

Of more immediate concern for Trump however is a split among Republicans.

The reality TV star’s unorthodox style and hard-right message have left the party more divided than it has been in a generation.

Melania Trump, along with the candidate’s son and daughters, will all be rolled out at the convention in an attempt to humanize The Donald.

Polls show that Trump struggles badly with moderate voters, and his campaign will want to project a more positive image to the general electorate.

Trump’s choice of Indiana governor Mike Pence as his vice presidential running mate could help shore up his position among conservatives, although the real estate billionaire seemed tepid about his decision.

In a remarkable first joint appearance on Saturday, Trump eventually got around to taking about Pence and explained why he was picked, in less than enthusiastic terms.

“One of the reasons is party unity, so many people have said, ‘party unity.’ Because I’m an outsider.”

Trump campaign chair Paul Manafort insisted that there was unity. “This is a Trump convention. The party is united,” he said.

“It’s a few people who are holding up and they don’t reflect anything other than their personal opinion.”

Inside the halls it remains to be seen if the “Never Trump” camp will make themselves heard.

Outside, however, law enforcement is bracing for a wave of protests.

Roads in the Ohio city are lined with concrete barriers and helicopters buzz overhead.

Cleveland, a Midwestern city of nearly 400,000, has taken out $50 million in protest insurance.

Ohio’s open-carry law, which allows people with proper permits to carry a loaded weapon on the streets, is adding to fears of violence.

“We have policies in place for mass arrests through our prosecutor’s office, our clerk’s office and our court system,” Cleveland police chief Calvin Williams told reporters.