5 Things to Watch on the First Day of the RNC

— -- Today is the official start of the Republican National Convention, but there's already action brewing in Cleveland.

Here are some key storylines to keep an eye on as the convention begins.

Security Concerns

Security around the Republican National Convention has been an area of concern for law enforcement officials for weeks, and recent domestic and international events have heightened those concerns.

Thousands of law enforcement officers were ordered to Ohio even before the fatal shootings of police officers in Baton Rouge, Louisiana. After yet another tragedy, the head of Cleveland's largest police union called for an emergency action to be taken to suspend the state's open carry laws during the convention.

Still, Cleveland Police Chief Calvin Williams stressed officers are "prepared for anything and everything" that could happen.

Melania Speaks

Donald Trump's campaign chairman, Paul Manafort, confirmed that Melania Trump will address the convention on the first night of the event.

Sources tell ABC that she spent the weekend preparing for the address in New Jersey.

The campaign has released no information about her speech's focus or its length, but those sources did not rule out the prospect of her husband's making an earlier-than-normal appearance at the convention in order to introduce his wife.

Melania Trump, a former model and Donald Trump's third wife, has not been an active force on the campaign trail, saying that she was going to be spending more time at home with the couple's 10-year-old son, Barron. She gave a speech in Wisconsin in April in a bid to help the campaign gain some traction with female voters, a group that Donald Trump has struggled to win over.

Who Else Will Be Taking the Stage

Melania Trump isn't the only boldfaced name who will be speaking today.

"Duck Dynasty" star Willie Robertson and actors Scott Baio and Antonio Sabato Jr. are slated to speak on behalf of the reality star turned presumptive Republican nominee.

The campaign unveiled that each night will be shaped by a theme, and today's will be "Making America safe again," so it fits that the campaign will feature two U.S. Marine Corps veterans, along with former New York City Mayor Rudy Giuliani and Lt. Gen. Michael Flynn.

It's Really the Second Week of Work for Republicans

Some of the most important decisions that will affect the convention were made last week during the RNC rules committee meetings, where a group of delegates set the rules for the convention and the official positions of the Republican Party.

Last-ditch efforts from Donald Trump opponents to let delegates vote for whomever they choose — which could have allowed for scuttling Trump's nomination — failed during those meetings, and the movement's leader told ABC News she would not attempt to force a vote at the convention.

Some efforts continue even as the convention gets underway. Anti-Trump delegates are hoping to block the entire rules package and persuade their colleagues to go rogue, encouraging them not to stick to their binding votes and to force recounts in their state delegations.

The Delegates Decide Their Rules and Platforms

The biggest assignment that delegates have today is voting on their party's platform and the rules of the convention, both of which were lined up in the rules committee meetings.

The GOP took hard positions on same-sex marriage and transgender restroom use, and establishment Republicans fended off attempts to strip power from the Republican National Committee and make the rules friendlier to conservatives.

ABC News' Ryan Struyk contributed to this story.