Donald Trump's vice-presidential running mate, U.S. Senator J.D. Vance, presented himself to the nation on Wednesday night as the son of a forgotten industrial Ohio town who will fight for the working class if elected in November.

In chronicling his hardscrabble journey from a difficult childhood to the U.S. Marines, Yale Law School, venture capitalism and finally the U.S. Senate, Vance, 39, introduced himself to Americans while using his story to argue that he understands their everyday struggles.

"I grew up in Middletown, Ohio, a small town where people spoke their minds, built with their hands and loved their God, their family, their community and their country with their whole hearts," Vance said, formally accepting the party's nomination at the Republican National Convention in Milwaukee.

"But it was also a place that had been cast aside and forgotten by America's ruling class in Washington."

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He accused "career politicians" like U.S. President Joe Biden — who Vance noted has been in politics longer that he has been alive — of destroying communities like his with ill-fated trade policies and foreign wars.

"President Trump's vision is so simple and yet so powerful," he said. "We're done, ladies and gentlemen, catering to Wall Street. We'll commit to the working man."

In a sign of his potential value to the ticket, he also repeatedly appealed to the working and middle classes in Michigan, Pennsylvania and Wisconsin specifically — three Rust Belt swing states likely to decide the Nov. 5 election.

Vance described his grandmother, "Mamaw," who raised him as his mother struggled with addiction — and acknowledged his mother, Beverly, who was on hand to watch him speak.

"I am proud to say that tonight my mom is here, 10 years clean and sober," Vance said. "I love you, Mom."

A visibly moved Beverly Vance mouthed, "I love you, J.D.," while delegates gave her a standing ovation.

Vance described his grandmother as someone who both "loved the Lord," but also "loved the F-word."

"She was an old woman who could barely walk, but she was tough as nails," Vance said.

Fast rise to VP nomination

Vance's prime-time debut, less than two years after he first assumed public office, capped a rise that coincided with his transformation from a fierce Trump detractor to one of his most devoted defenders.

He is one of several high-profile Republicans, such as U.S. senators Ted Cruz and Marco Rubio, whose reversal from critic to loyalist has underscored Trump's takeover of the party.

WATCH | Vance says a 2nd Trump administration would focus on keeping jobs in America: 

J.D. Vance vows an 'American-made' approach

Vice-Presidential candidate J.D. Vance drew applause from the crowd at the Republican National Convention when he promised that a second Trump administration would focus on American manufacturing, and in doing so, fend off foreign companies from dominating American marketplaces.

Author of the bestselling memoir Hillbilly Elegy, Vance has helped to shape Trump's populist instincts into a policy agenda that would pull the U.S. back from its dominant role in global affairs.

As the first millennial on a major party's ticket, he is well positioned to carry Trump's Make America Great Again movement beyond a potential second Trump term.

His speech embraced many of the core tenets of Trumpism, promising to prioritize domestic manufacturing over Chinese imports and warning allies they would no longer get "free rides" in securing world peace.

Vance has opposed military aid for Ukraine and defended the 78-year-old Trump's attempts to overturn his 2020 election loss to Biden.

He has argued the government must do more to assist the working class by restricting imports, raising the minimum wage and cracking down on corporate largesse. Those positions, at odds with the Republican Party's traditional pro-business stance, nonetheless track Trump's program closely.

Democrats have already gone on offence against Vance, highlighting his strict anti-abortion views and arguing that he will advance an extreme, far-right agenda in office.

When winding down his speech, Vance thanked Trump for "the trust you have put in me," and pledged to give his best to Americans no matter what party they support.

Biden, meanwhile, was forced off the campaign trail on Wednesday after testing positive for COVID-19.

The illness added to the 81-year-old president's woes, after three tumultuous weeks in which he has struggled to reassure panicked Democrats that he can still defeat Trump following an anemic debate performance late last month.