MILWAUKEE (AP) — Donald Trump’s running mate JD Vance will introduce himself to a national audience Wednesday night as he addresses the Republican National Convention.

The Ohio senator’s headlining address will be his first speech as the Republican vice-presidential nominee. In fact, this year’s gathering also is the first RNC that Vance has attended, according to a Trump campaign source who was not authorized to speak publicly. A relative political unknown, Vance rapidly morphed in recent years from a severe critic of Trump to an aggressive defender.

The 39-year-old is positioned to become a potential leader of the former president’s political movement, which has reshaped the Republican Party and broken longtime political norms. The first millennial to join a major party ticket, he joins the race when questions about the age of the men at the top — 78-year-old Trump and 81-year-old President Joe Biden — have been high on the list of voters’ concerns.

Republican vice presidential candidate Sen. JD Vance, R-Ohio is introduced during the Republican National Convention Tuesday, July 16, 2024, in Milwaukee. (AP Photo/Paul Sancya)
Republican vice presidential candidate Sen. JD Vance, R-Ohio is introduced during the Republican National Convention Tuesday, July 16, 2024, in Milwaukee. (AP Photo/Paul Sancya)

Vance is expected to lean into his biography as someone who grew up poor in Kentucky and Ohio, his mother addicted to drugs and his father absent, but went on to the highest levels of US politics. It’s a story meant to connect with voters in middle America and shed light on how Vance’s upbringing shaped his positions on issues such as immigration, inflation and drugs, according to a person familiar with the speech who was not authorized to speak publicly about it.

An Ivy League graduate and a businessman, Vance’s memoir, “Hillbilly Elegy ” explored his blue-collar roots and made him a national name when it was published in 2016. The book is now seen as a window into some of the cultural forces that propelled Trump to the White House that year.

Trump, as the presidential nominee, is expected to speak Thursday, the convention’s final night. It will be his first speaking event since he survived an assassination attempt at a rally in Pennsylvania on Saturday.

Beyond Vance’s prime-time speech, the Republican Party intends to focus Wednesday on a theme of American global strength.

Republicans contend that the country has become a “global laughingstock” under Biden’s watch and are expected to make a case Wednesday hitting on their theme to “Make America Strong Once Again.” That’s expected to include Trump’s “America First” foreign policy that redefined relationships with some allies and adversaries.

Democrats have sharply criticized Trump — and Vance — for their positions, including questioning U.S. support for Ukraine in its defense against Russia’s invasion.

In a video released Wednesday by Biden’s reelection campaign, Vice President Kamala Harris dismissed Vance as someone Trump “knew would be a rubber stamp for his extreme agenda.”

“Make no mistake: JD Vance will be loyal only to Trump, not to our country,” Harris says in the video.

Vance was a harsh critic of Trump at the time he was first elected, referring to him in interviews as “noxious” and someone who “is leading the white working class to a very dark place.” He even once referred to him as “America’s Hitler.”

He began warming to Trump over the years, especially as he sought in 2022 to run for the U.S. Senate. Vance won Trump’s endorsement, which helped him secure the party’s nomination for the Ohio Senate seat.

Vance has become one of Trump’s most aggressive defenders as the former president has sought the office a third time, sparring with journalists, campaigning on his behalf and appearing with the candidate at his trial in New York.

In his first interview after accepting Trump’s offer to join the ticket, Vance sought to explain his metamorphosis. Vance said in a Fox News Channel interview Monday that Trump was a great president and changed his mind.

“I think he changed the minds of a lot of Americans, because again he delivered that peace and prosperity,” Vance said.

Donald Trump Jr., the former president’s son and a close friend of Vance, is also slated to speak Wednesday, according to a person close to Trump Jr. who spoke on condition of anonymity because the official speaking schedule has yet to be released.