WASHINGTON – JD Vance has come to be known as one of the top next-generation leaders of the populist conservative movement President-elect Donald Trump sparked. Now he will officially be Trump's heir apparent as vice president of the United States.

It has been a remarkable rise for the junior senator from Ohio, who gained national fame in 2016 as the author of a best-selling memoir, "Hillbilly Elegy," and who, at just 40 years old, will be one of the youngest vice presidents in American history.

Vance expects his job as vice president will be "very active," he told USA TODAY in September. "I know the president wants me to be involved in everything, and I certainly hope to be."

Vance has evolved from a never-Trump Republican to a loyalist who has frequently been thought of as one of the leading heirs to Trump's brand of conservative politics.

After a childhood marked by family addiction and abuse in a struggling industrial town, Vance joined the Marine Corps and climbed his way to the elite circles of Yale Law School and Silicon Valley.

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His memoir illustrated some of the working class frustrations that led to Trump's first victory in 2016, and laid the groundwork for issues that would become central to his politics today – criticism of foreign intervention, free trade policies and betrayal by America’s elites.

Vance became a translator of those working class woes in liberal and centrist circles confused by Trump's rise, even as he called Trump "noxious" and "reprehensible" in public and "America’s Hitler” in private.

Over the next few years ahead of his election to the Senate in 2022, Vance would undergo a conversion that made him one of the top messengers in the media for Trump's MAGA movement. He was persuaded to look past Trump's demeanor and found he preferred his policies, Vance has said, while his critics have argued it is evidence he is duplicitous and willing to do anything for power.

“I think that it actually makes him more relatable and even a better VP pick than others because he was a little Trump-skeptical early on,” Turning Point USA founder Charlie Kirk told USA TODAY earlier this year. “He became a believer as he saw that President Trump implemented policies and decisions that were consistent with what he believes in. I think it’s more genuine and real.”

Campaign victories and stumbles

Vance was deployed on the campaign trail to defend the president at fundraisers, rallies and news programs that weren't always friendly to him.

He emerged as the clear winner of the only vice presidential debate against Minnesota Gov. Tim Walz, who lacked Vance's ease in front of the cameras, and he has regularly ended his rallies by taking questions from reporters.

Vance stood with the president-elect throughout his most controversial moments of the campaign, including falsely claiming Trump won the 2020 presidential election and defending Trump's claim that Haitian immigrants in Springfield, Ohio were eating residents' pets, which he said he'd heard firsthand from constituents but which local officials said was not true.

But he also stirred his own share of controversy. Old comments in which Vance called Vice President Kamala Harris one of the "childless cat ladies" running the country went viral shortly after he accepted the nomination, along with other past statements suggesting that parents should have greater voting rights than childless adults.

Videos of awkward campaign encounters and stump jokes fed ridicule from the left. The combination became fodder for Walz to coin the term "weird" to describe those at the top of the Republican ticket.

Trump picked Vance when he believed he was heading to victory in an easy race against President Joe Biden. When Biden dropped out of the race and Trump found himself up against a younger, more popular Democratic candidate, it prompted speculation that Republicans were regretting the choice of running mate – a rumor the campaign pushed back on.

Vance's short Senate tenure

Vance's election to the vice presidency will create an opening in his Ohio Senate seat, where he will have served for only two years.

Vance will have to resign before taking the oath of office on Jan. 20 and Ohio's Republican Gov. Mike DeWine will appoint a replacement until the state can hold a special election to fill his seat through the end of his term in 2028.

Despite his short tenure in the Senate, Vance became known as one of the chamber's leading critics of additional federal aid for Ukraine, arguing the effort mirrored misguided support for the War in Iraq. It put him at odds with the leader of his own conference, Senate Minority Leader Mitch McConnell, R-Ky.

But he's also demonstrated a willingness to work across the aisle with populist senators of both parties on key economic issues. He pushed for action on internet affordability, worked with Sen. Elizabeth Warren, D-Mass., to crack down on the executives of failed banks and with Sen. Sherrod Brown, D-Ohio, to strengthen federal rail safety rules.

As vice president, he is expected to continue to advocate for the issues that he touted on the campaign trail, including foreign isolationism, increased domestic oil production, tighter border security.

Multiple conservative leaders have told USA TODAY they believe he models the future of the Republican Party.

Ohio Republican Party Chair Alex Triantafilou told USA TODAY in September he represents "a realignment" of the party to focus on "working class Americans who feel like they're left behind in a globalist economy."

And Kevin Roberts, president of the conservative think tank the Heritage Foundation, said both he and Vance believe "there needs to be a new conservative movement" incorporates new ideas to longstanding policy goals and brings in new constituencies. “I think that Sen. Vance is the leader of that effort, at least among elected officials in DC."