MILWAUKEE >> Former President Donald Trump has chosen Sen. J.D. Vance of Ohio to be his running mate, wagering that the young senator will bring fresh energy to the Republican ticket and ensure that the movement Trump began nearly a decade ago can live on after him.

Vance, 39, is a political newcomer who entered the Senate only last year, but he has spent that time methodically ascending the conservative firmament. Once an acerbic Trump critic — attacking Trump as “reprehensible” and calling him “cultural heroin” — he won Trump’s backing in his 2022 Senate race by wholly embracing his politics and his lies about a stolen election. The endorsement lifted him above a crowded field, and ultimately to the Senate.

Vance, a venture capitalist in Silicon Valley who became best known for writing the memoir “Hillbilly Elegy,” did not forget it. He quickly emerged as a top defender of the former president in the halls of Congress and on television, taking his cues from Trump while frequently bucking the priorities of longtime Senate Republican leader Mitch McConnell.

Trump announced his choice in a post on his social media platform Truth Social today, as the Republican National Convention was getting underway in Milwaukee. He said Vance was “the person best suited” to be his potential vice president. He highlighted Vance’s time in the Marine Corps and his memoir, saying he believed Vance was a champion for hardworking people.

Trump’s selection came just days after he survived an assassination attempt at a rally in Pennsylvania, an episode that underlined the significance of his choosing a running mate who might be in line as Trump’s successor.

In Vance, Trump has tapped an ambitious ideologue who relishes the spotlight and has shown he can energize donors on behalf of the presumptive nominee. His youth — there are nearly 40 years separating them, and Vance is the first millennial nominated to a major-party ticket — could prove a boon to the ticket, as voters have expressed concern over both Trump’s and Biden’s ages.

Vance achieved renown after the publication in 2016 of “Hillbilly Elegy,” about growing up poor in Ohio and Kentucky. The timing dovetailed with Trump’s political rise, and Vance, then a “Never Trump” conservative, became sought out for his perspective on what fueled Trump’s popularity among white working-class voters.

But Vance said his views shifted during the Trump presidency. And by the time he entered the Republican primary for a Senate seat in Ohio in 2021, he had adopted Trump’s hard-right messaging and renounced his previous views about immigration and trade.

This article originally appeared in The New York Times.