US Senator J.D. Vance was set to debut on the national stage Wednesday in his first address as the Republican vice-presidential nominee -- completing a meteoric rise from humble midwestern beginnings to a coveted spot on Donald Trump's ticket.
Trump tapped the Ohio conservative to be his number two at the Republican National Convention in Milwaukee on Monday as the ex-president bids for a stunning return to the White House, four years after losing to President Joe Biden.
The one-term senator, who turns 40 next month, would be the third-youngest vice president in history -- and one of the least experienced -- if Trump prevails in his rematch against Biden in November.
Vance was an uncompromising "Never Trumper" at the time of his new boss's election win in 2016, labeling the tycoon a "a moral disaster" and comparing him to Adolf Hitler.
But he reinvented himself as an ultra-loyal acolyte when he entered politics and ultimately won the ex-president's endorsement in the 2022 Ohio Senate race.
"I was certainly skeptical of Donald Trump in 2016. But President Trump was a great president, and he changed my mind," Vance told Fox News on Monday.
Despite making his name with the 2016 memoir "Hillbilly Elegy," a best-selling account of his Appalachian family and modest Rust Belt upbringing, he remains something of an unknown quantity to the wider public.
Many voters will be seeing him for the first time as Wednesday's prime-time speech is beamed into living rooms across America.
He is already a hit with the party faithful in Milwaukee, who rewarded him with a rowdy ovation as he stepped on the convention floor with his wife, Usha, on Monday.
Vance embraces Trump's isolationist, anti-immigration America First movement, but offers little chance of expanding the ticket's appeal to more moderate voters and women.
He is further to the right than Trump on some issues including abortion, where he embraces calls for federal legislation.
"As Vice President, J.D. will continue to fight for our Constitution, stand with our Troops, and will do everything he can to help me MAKE AMERICA GREAT AGAIN," Trump gushed on his social media platform Truth Social Monday.
Some 50,000 Republicans have descended on the shores of Lake Michigan for the four-day Republican National Convention, which comes with the country reeling from a botched attempt by a gunman to kill Trump at a rally in Pennsylvania on Saturday.
The attack -- which killed one bystander and left the ex-president with a bloodied ear -- has dominated proceedings, with the opening day's highlight an appearance from a defiant Trump sporting a bandage on his right ear.
Trump said after the shooting he hoped to "unite our country" and yet his running mate has been one of the most partisan and divisive members of Congress.
The firebrand immediately blamed Democrats for the attack, saying anti-Trump rhetoric "led directly to President Trump's attempted assassination."
The second day of the convention was intended to project a united Republican Party, as Trump's defeated rivals in the contest for the nomination lined up to lavish him with praise.
One-time UN ambassador Nikki Haley, who was greeted with muted applause and a smattering of boos, told delegates "a unified Republican Party is essential" for saving the nation.
Trump showed up again, still sporting the bandage and waving as delegates burst into applause.
While he made no formal remarks, the 78-year-old slapped backs and chatted with Vance, pumping his fist and looking more relaxed than during his emotional entrance the previous night.
The Republican leader has been widely feted at the convention, where on Thursday he is set to formally accept his party's nomination with the hotly-anticipated keynote address.
