George Stephanopoulos: What You Need to Know About RNC Day 3

There's a lot to look forward to on day three of the Republican National Convention, with big political names scheduled to speak. ABC News' George Stephanopoulos looks ahead at the top story lines to watch for tonight.

Mounting Accusations of Recycled Lines

One night after Melania Trump delivered speech lines nearly identical to Michelle Obama's, Donald Trump Jr. appeared to recycle one written months earlier by his convention-night speechwriter.

"Our schools used to be an elevator to the middle class. Now they are stalled on the ground floor," Trump Jr. said Tuesday night in Cleveland, delivering one of the keynote speeches of the day at the Republican National Convention. "They are like Soviet-Era department stores that are run for the benefit of the clerks and not the customers."

That Soviet-department-store comparison closely matched one from George Mason University law professor Frank Buckley. Both Buckley and the Trump campaign told ABC News that Buckley worked as a speechwriter on Trump Jr.'s address.

Trump campaign chairman Paul Manafort, who has flatly denied that Melania Trump's speech was plagiarized, told Stephanopoulos on ABC News' "Good Morning America" that such accusations shouldn't be an issue going forward.

"I think they finally figured out how to get one of those [software] programs that's going to prevent that," Stephanopoulos said.

Eric Trump Takes the Stage

Donald Trump's 32-year-old son from his first marriage will address the audience at the Quicken Loans Arena in Cleveland for the first time tonight. In an interview on "GMA" this morning, Eric Trump promised that his speech will be in his own words and will come from his heart.

"Zero," he said when asked whether any speechwriters helped compose his address in support of his father. "I wrote every single word of my speech myself."

Eric Trump did not comment on his stepmother's speech, which has been the center of much controversy. He did say that his address tonight will "focus on the why" of his father's campaign, why Donald Trump would forgo his success in New York City to put himself in the spotlight and rigor of the campaign trail.

"I really focus on the why because I think it's such an important question," Eric Trump said on "GMA." "Here's a guy who is kind of in the apex of his career. He does not need to be doing this.

He added: "My father cares deeply about this country. This country has given him everything."

Mike Pence's Big Night

It's the first time much of the nation will see Mike Pence since Donald Trump formally introduced the Republican Indiana governor as his running mate Saturday before the convention. Donald Trump admitted that one of the main reasons he chose Pence is "party unity."

"I have to be honest. So many people have said 'party unity,' because I'm an outsider," Trump said while officially introducing his pick for vice president.

The Trump takeover of the Republican Party was formalized Tuesday night, amid some folded arms on the floor of a Republican National Convention that has lacked unity and energy. Bringing the party together in support of a Trump presidency is something Pence must tackle tonight as the headline speaker.

"Of course, he's got a big job to speak to the country," Stephanopoulos said. "But also to really do more to unite this hall behind Donald Trump. It's been kind of flat."

Trump Policies

So far, Hillary Clinton has dominated the topics discussed by the cavalcade of speakers from various backgrounds who have made their way to the podium at the Republican National Convention. In total, an ABC News review of transcripts found almost 200 references to Clinton throughout all speeches during the first two days of the convention.

There has been no talk of Donald Trump's controversial proposals, including his plan to build a wall between the United States and Mexico, which he says the latter will pay for, nor his proposed temporary ban on Muslims' entering the country. It remains to be seen whether the GOP presidential nominee or another speaker will address such topics at the convention this week.

"Nothing about that wall on the border paid for by Mexico, nothing from the podium about the Muslim ban, nothing about scrapping trade agreements and having 35 percent tariffs with China," Stephanopoulos said. "Those issues have really been tamped down. We haven't heard about it at all."

ABC News' Chris Good, Meridith McGraw, Katie Kindelan and Adam Kelsey contributed to this report.