The first day of the Republican National Convention came with a big reveal: J.D. Vance is Donald Trump's choice to be his running mate in the 2024 election.
The 39-year-old senator was met with rousing cheers as he walked onto the convention floor, where he stopped for selfies and to shake hands as he made his way toward the Ohio delegation.
The biggest applause, however, came moments later when Speaker Mike Johnson announced the joint Trump-Vance ticket.
ABC News spoke with delegates outside the convention center just after Vance's appearance. Many described him as someone they could see being a faithful messenger of Trump's agenda, even if they hadn't heard much about him before.
"I think it was a great selection by President Trump because Senator Vance's conservative bona fides have been proven time and time again," said John Merrill, a delegate from Alabama.
Merrill said he believed Vance would support Trump in nominating conservative judges and to carry out his immigration policies, including finishing the border wall.
Ohio State Rep. Cindy Abrams, a member of the Ohio delegation, praised Vance as someone who "supports law enforcement and law and order, most importantly securing our border."
"I was really excited to hear J.D. Vance," said Geraldine Wade, an alternate delegate from Georgia. "Everybody kept guessing, 'Who is he gonna pick?' but we wanted somebody who was adopting the MAGA agenda."
"He has the youth and he has the enthusiasm and we think he would be a good person to carry on the agenda of Donald Trump," Wade added.
Delegates from the Ohio delegation said they were "very excited" and "proud" about his nomination.
"We're psyched that J.D. has taken up the mantle and sacrificed for his country and for our state Ohio, and we're thankful to his family for also taking up this grave responsibility," one member of the delegation said.
But Vance, a first-term senator, was little known in political circles until his memoir "Hillbilly Elegy" catapulted him into the national spotlight. He won his seat in the Senate in 2022 with the support of Trump, despite having once declared himself a "never-Trumper" -- statements he's long since reversed.
Also Trump's list of potential vice presidential picks were Florida Sen. Marco Rubio and North Dakota Gov. Doug Burgum. Both Rubio and Burgum were notified that they were not selected, ABC News reported earlier Monday.
"Everybody has their own favorite candidates but I think Senator Vance was on everybody's list," Merrill said of the vice presidential contenders. "He may not have been everyone's favorite but he is certainly our favorite today."
"I think that's a fantastic pick," said Bill Oden, a delegate from South Carolina. "I know he wasn't on the radar but the fact he's a fellow service member -- I'm retired Air Force and he's a Marine -- it's great to have a vice president that's got military experience so he can advise the president on a lot of the actions we are going to be facing in the future."
"I really don't know him, so it's great to have a new face," said convention attendee Mary-Beth Checkai. "It's great to have changes. He's young. He served in the military, so he's got values. And he's got a family to protect, so I think it's a great choice to move the party forward."
Vance enlisted in the Marine Corps and served in Iraq as a corporal with the public affairs section of the 2nd Marine Aircraft Wing.
Other veterans at the RNC also praised his background.
Tiffanie Ditlevson, an Air Force veteran who is now serving as a city council member in Indiana, said she hopes it will inspire young people to consider a career in the military.
"I think it balances Trump in a different way," she said of Vance being selected as his running mate. "I think definitely President Trump brings a lot to the table in terms of being an executive and running the country and his perspective and mindset, and then also having a veteran in there."