With an eye toward the future of a Republican Party dominated by former President Trump and his legions of MAGA supporters, Trump has named 39-year-old Sen. JD Vance of Ohio as his running mate on the GOP'S 2024 national ticket.

The former president, who made his greatly anticipated and high-stakes announcement on Monday as the Republican National Convention kicked off in swing-state Wisconsin's largest city, will now share the ticket with one of his top supporters in the Senate and a one-time Trump critic who has transformed into a leading America First disciple.

"After lengthy deliberation and thought, and considering the tremendous talents of many others, I have decided that the person best suited to assume the position of Vice President of the United States is Senator J.D. Vance of the Great State of Ohio," Trump announced on his Truth Social platform.

Trump emphasized that Vance, on the campaign trail "will be strongly focused on the people he fought so brilliantly for, the American Workers and Farmers in Pennsylvania, Michigan, Wisconsin, Ohio, Minnesota, and far beyond…."

Vance appeared on the floor of the convention hall of the Fiserv Forum, where the four-day Republican National Convention kicked off this afternoon. He shook hands with friends and supporters in the Ohio delegation during the vice presidential nomination roll call.

Vance, a former venture capitalist and the author of the bestselling memoir, "Hillbilly Elegy," before running for elective office, was one of a handful of Republicans considered top running mate contenders. That group also included North Dakota Gov. Doug Burgum and Sen. Marco Rubio of Florida.

While Vance hails from Ohio, a one-time battleground state the former president comfortably carried in the 2016 and 2020 elections, the senator's selection is expected to boost Trump among working-class Democrats, especially across the Rust Belt, who otherwise might have been supporters of President Biden, according to multiple experts who spoke with Fox News Digital as Trump was weighing his options.

Vance grew up in a working-class family in a small city in southwestern Ohio. His parents divorced when he was young, and as his mother struggled for years with drug and alcohol abuse, Vance was raised in part by his maternal grandparents.

After high school graduation, Vance enlisted in the U.S. Marine Corps and served in the Iraq War. He later graduated from Ohio State University and then earned a law degree at Yale University.

Vance, who lives in Cincinnati, moved to San Francisco after law school and worked as a principal in a venture capital firm owned by billionaire venture capitalist Peter Thiel, who later became a major financial supporter of Vance's successful 2020 campaign for the Senate.

Before running for Senate, Vance grabbed national attention after "Hillbilly Elegy" – which tells his story of growing up in a struggling steel mill city and his roots in Appalachian Kentucky – became a New York Times bestseller and was made into a Netflix film. The story spotlighted the values of many working-class Americans who became supporters of Trump's policies.

Vance was a vocal critic of Trump when the former president first ran for the White House in the 2016 cycle. 

However, Vance eventually supported Trump, praising the former president's tenure in the White House, and in a Fox News interview in 2021, he apologized for his earlier criticism of Trump.

Trump's endorsement of Vance days before the 2022 GOP Senate primary boosted him to victory in a crowded, competitive and combustible nomination race.

"Look, I was wrong about Donald Trump. I didn't think he was going to be a good president," Vance told Fox News' Bret Baier in an interview last month. "He was a great president, and it's one of the reasons why I'm working so hard to make sure he gets a second term."

In the Senate, Vance has been one of the most vocal supporters of Trump's America First agenda and has been a vocal opponent of U.S. aid to Ukraine.

During the vetting process for the vice presidential nominee, Vance had a major ally in Donald Trump Jr. The former president's eldest son and popular surrogate in the MAGA world is a close friend of Vance.

The elder Trump has also appeared to build a friendship with Vance. The former president likened Vance to "a young Abraham Lincoln" while speaking with Fox News' Brian Kilmeade last week following a report that said he found facial hair like Vance's to be distasteful.

"No. I've never heard that one," Trump said when asked about the report, which suggested Vance's facial hair could potentially hinder his selection as his running mate. "He looks good… He looks like a young Abraham Lincoln."

Minutes after the announcement, Trump's campaign posted a new image and logo of the GOP's 2024 national ticket.

Vice President Kamala Harris reached out to Vance "and left a message to congratulate him on his selection, welcome him to the race and express her hope that the two can meet in the vice presidential debate," the Biden campaign told Fox News.

President Biden, reacting to the news Vance was named as Trump's running mate, wrote in a social media fundraising pitch, "Here’s the deal about J.D. Vance. He talks a big game about working people. But now, he and Trump want to raise taxes on middle-class families while pushing more tax cuts for the rich."

"Well, I don’t intend to let them," the president emphasized.

And the president's re-election campaign was quick to illustrate Vance as a champion of Trump's MAGA movement.

Biden campaign chair Jen O'Malley Dillon argued in a statement that "Trump picked J.D. Vance as his running mate because Vance will do what Mike Pence wouldn’t on January 6: bend over backwards to enable Trump and his extreme MAGA agenda, even if it means breaking the law and no matter the harm to the American people."

Fox News reported earlier on Monday afternoon that Burgum and Rubio were informed ahead of the Vance announcement that they would not be named as the running mate.

Burgum, in a social media post, wrote that Vance's "small town roots and service to country make him a powerful voice for the America First Agenda. I look forward to campaigning for the Trump-Vance ticket to Make America Great Again!"