RNC Day 3: JD Vance accepts nomination for vice president as Trump watches on

J.D. Vance is speaking in primetime at the RNC, live on all three big networks as well as cable news.

The stakes are high, as this is the first impression many Americans will have of him.

According to a recent YouGov poll, 43 percent of Americans don't have an opinion of Vance -- probably because many of them are hearing about him for the very first time.

This speech will be step one in (he hopes) building a positive reputation for himself.

The conventional wisdom is that presidential candidates should pick running mates who will give them a boost in a key swing state. But Trump didn't do that: Vance is from Ohio, a state that used to be pivotal in presidential elections but has now become pretty reliably Republican. (Trump won it by 8 points in 2020 even as Biden was winning nationwide by a healthy margin.)

Was that a missed opportunity for Trump? Probably not: It turns out that vice-presidential candidates barely matter. Historically, they have been worth about 1 additional percentage point in their home state -- if that -- and don't make a difference in other states. So while Vance might be worth a few extra votes in Ohio, his selection is unlikely to move the needle even in neighboring states such as Pennsylvania and Michigan and probably won't affect the election outcome.

-538's Nathaniel Rakich

Usha Vance, J.D. Vance's wife and political unknown, arrived on the RNC stage for her prime-time debut.

"When I was asked to introduce my husband J.D. Vance to all of you, I was at a loss," she said. "What can I say that hasn't already been said. I mean the man was a subject of a Ron Howard movie."

Vance has left her law firm following her husband being formally announced as former President Donald Trump's running mate at the Republican National Convention on Monday.

Before leaving the firm, Usha's practice focused on "complex civil litigation and appeals in a wide variety of sectors, including higher education, local government, entertainment, and technology, including semiconductors," according to her biography page on the firm's website, before it was removed.

Usha previously served as a law clerk for Chief Justice John G. Roberts, Jr. of the U.S. Supreme Court, Judge Brett Kavanaugh, then of the U.S. Court of Appeals for the District of Columbia Circuit and Judge Amul Thapar, then of the U.S. District Court for the Eastern District of Kentucky, according to the firm.

Born Usha Chilukuri, the wife of the newly announced VP pick, grew up in San Diego, California, and is the daughter of Indian immigrants.

She received her law degree from Yale Law School and, during her time at the institution, served as executive development editor of the Yale Law Journal and managing editor of the Yale Journal of Law & Technology, according to her biography page.

J.D. and Usha met during their time at Yale Law School and got married in Kentucky in 2014, according to the New York Times.

The Associated Press contributed to this report.

Multiple Republican senators chased down U.S. Secret Service Director Kimberly Cheatle after they spotted her at the RNC on Wednesday.

Tennessee Sen. Marsha Blackburn was one of the senators and shared a video of the confrontation on her X page, where she accused Cheatle of "stonewalling" them as she refused to respond to their repeated jeers.

The Secret Service director was chased by senators at the RNC Wednesday.

"This was an assassination -- you owe the people answers, you owe President Trump answers," Blackburn can be heard saying in the video.

Multiple sources, who verified the authenticity of the video, told ABC News that the Secret Service director was on the suite level of the convention hall.

-ABC News' Allison Pecorin and Katherine Faulders

An aircraft entered the restricted airspace surrounding the Republican National Convention in Milwaukee on Wednesday and was escorted out of the area by a North American Aerospace Defense Command F-35 jet.

The aircraft was not in communication with air traffic control when flying about 24 miles southwest of Milwaukee around 3:30 p.m., NORAD said. The F-35 jet was flying at about 4,000 feet and would have been visible from the ground, NORAD said.

NORAD did not provide any details about the type of aircraft it intercepted, where it was headed or if it knew it was violating the restricted airspace.

The Federal Aviation Administration has implemented temporary flight restrictions in and around Milwaukee throughout the convention which concludes Thursday.