David Jackson

USA TODAY

CLEVELAND — A speech by Melania Trump highlights the opening night of the Republican convention on Monday, a program that may also include, perhaps, an appearance from husband and nominee-in-waiting Donald Trump, GOP officials said Sunday.

Top Trump campaign aide Paul Manafort declined to comment on whether the Republican nominee-in-waiting would attend his wife's speech, saying "we'll deal with that tomorrow."

Saying the party has now united behind the maverick businessman, Manafort himself said "It's going to be a solid convention."

While Trump himself and new running mate Mike Pence stayed off the campaign trail Sunday, convention officials put the final touches on the convention hall, the security set-up, and the schedule of events.

"I can assure you that the city's going to be safe," said Republican National Committee Chairman Reince Priebus, speaking on Fox News Sunday. "And it's going to be a lot of fun."

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The program stayed in flux until the very last minute. A official close to the discussions, who asked not to be identified because he was not authorized to speak on the record, said Trump is fixated on injecting the program with non-traditional speakers, and a number of planned speeches are being rewritten, unusual for what it is normally a highly scripted affair.

Each night of the convention is devoted to a different theme playing off Trump's "Make America Great Again" slogan, according to the schedule released: "Make America Safe Again," "Make America Work Again," "Make America First Again," and "Make America One Again."

Speakers over the course of four nights range from Trump's children to House Speaker Paul Ryan to actor Scott Baio — a group that the RNC described in a statement as "an unconventional lineup of speakers who have real-world experience and will make a serious case against the status quo and for an agenda that will make America great again."

Also on the schedule: former Trump opponents like Sen. Ted Cruz of Texas and Marco Rubio of Florida — though Rubio has said he will not be attending the convention.

The Democrats have already slotted in speakers for their convention next week. Asked why the GOP held off until the afternoon before the convention, Priebus told Fox that "it's not disorganized, I think it's just different."

Besides, he said, the most important speech is pre-scheduled: Trump's nomination acceptance speech Thursday night.

"Thursday night is a really big deal for our party," Priebus said.

The campaign of Democratic candidate Hillary Clinton responded to the Republican schedule by putting out a fake speaker's list that included Republicans who will not speak at the convention, having criticized Trump at one point or another. That group includes former Republican president (George W. Bush) and presidential nominees, Mitt Romney and John McCain.

Trump and Pence, meanwhile, conducted a joint interview this weekend broadcast Sunday on CBS' "60 Minutes.

Pence, who has criticized negative campaigning in the past, told CBS that Trump's efforts are more about issues.

"In the essay that I wrote a long time ago, I said campaigns ought to be about something more important than just one candidate's election," the Indiana governor said. "And this campaign, and Donald Trump's candidacy, has been about the issues the American people care about."

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For his part, Trump said he and Pence are "different people" and that he will to be more aggressive on the campaign trail.

For example, "I call her 'Crooked Hillary' — she's crooked Hillary," Trump told CBS. "I didn't ask him to do it, but I don't think he should do it because it's different for him."

Trump also took to social media to denounce the Sunday shootings of police officers in Baton Rouge, La., saying that "we grieve for the officers killed in Baton Rouge today. How many law enforcement and people have to die because of a lack of leadership in our country? We demand law and order."

In another message, Trump said the nations is "TRYING" to fight Islamic State terrorists, "and now our own people are killing our police. Our country is divided and out of control. The world is watching."

The security presence is heavy in downtown Cleveland, especially in the wake of the recent terrorist attack in Nice, France. A large chunk of downtown Cleveland has been cordoned off with gates. Security guards and metal detectors are much in evidence.

"We've got $50 million in federal security," Priebus told Fox. "We've got thousands of cops coming in from around the country, we've got Secret Service in full force and we're ready for everything."

Contributing: Heidi Przybyla