The Ohio senator mentioned speaking with someone who wondered if they would ever be able to buy a house. Vance then blamed the housing crisis on "Wall Street barons," who crashed the economy, causing workers who built houses to lose their jobs and wages to stagnate. Then, he contended, Democrats let millions of illegal immigrants into the country, further increasing home prices.

But the housing affordability crisis has skyrocketed under Biden not for any of those reasons, but because interest rates have risen sharply along with inflation. Home prices were high under the prior three presidents, but low interest rates kept mortgage rates down, and homes therefore still within reach for many, especially in places like Vance's home state of Ohio.

Now those mortgage rates have increased exponentially, putting previously costly but still affordable homes well out of the reach of most prospective first-time buyers. It's one of Biden's most intractable problems.

He's 39 and will be 40 by Election Day - by next month, in fact, the same age as Richard Nixon, when he was elected vice president in 1952.

Dan Quayle was elected George H.W. Bush's No. 2 at age 41 in 1988.

But Theodore Roosevelt was only 38 when he was elected vice president and assumed the White House at age 42 after President William McKinley was assassinated in 1901.

Even Roosevelt wasn't the youngest. John C. Breckinridge was just 36 when he took the vice presidency after the 1856 election.

J.D. Vance accepted President Donald Trump's ask to be his 2024 running mate in his primetime speech Wednesday night.

With a kiss to his wife, Vance walked on to the stage. Bowing his head and waving to the crowd, the 39-year-old Ohio senator, elected just 20 months ago, proclaimed, "Wow, wow!" as the crowd briefly chanted "J.D., J.D."

"My name is J.D. Vance, from the great state of Ohio," he said.

To the chance of OH-IO, he said, "We gotta chill with the Ohio, we have to win Michigan too."

He said, "Tonight is a night of hope. A celebration of what America once was, and with God's grace, what it will soon be again."

Vance paid respect to Trump before detailing his own life story.

Beverly Aikins, J.D. Vance's mother, who he writes about in detail in his memoir, is sitting in the Trump family box and receives a standing ovation when Vance mentions her name. He notes that she has been sober for over 10 years.

"Our movement is about single moms like mine, who struggled with money and addiction but never gave up," Vance said.

The Associated Press contributed to this report.

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