Trump was widely expected to name his running mate at the Republican National Convention, which began the same day.

"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 wrote in a post on his social media platform Truth Social. "J.D. honorably served our Country in the Marine Corps, graduated from Ohio State University in two years, Summa Cum Laude, and is a Yale Law School Graduate, where he was Editor of The Yale Law Journal, and President of the Yale Law Veterans Association."

Vance, author of "Hillbilly Elegy," was elected to the U.S. Senate in 2022 after a contentious primary election in the Buckeye State, in which he got Trump's endorsement, and was his first election to public office. Vance, who is Catholic, is married to Usha Vance, a litigator. The couple has three young children.

Trump said Vance "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."

Trump added that as vice president, Vance "will continue to fight for our Constitution, stand with our Troops, and will do everything he can to help me MAKE AMERICA GREAT AGAIN."

"Congratulations to Senator J.D. Vance, his wife, Usha, who also graduated from Yale Law School, and their three beautiful children," he said. "MAGA2024!"

Vance, was at one time a staunch critic of Trump, but became a closer ally of the former president as he campaigned for the U.S. Senate as a populist, and is ideologically aligned with Trump on issues such as foreign policy and immigration.

In his first television ad for his 2022 bid for the Senate, Vance said, "Joe Biden's open border is killing Ohioans," arguing that Bien's immigration policy led to "more illegal drugs and more Democrat voters pouring into this country."

Vance's 2022 campaign also distributed fundraising materials calling for the deportation of "every single person who invaded our country illegally."

According to the Migration Policy Institute, an estimated 11.3 million unauthorized immigrants lived in the U.S. as of mid-2022.

Legally, the U.S. uses the terms "removal" or "return" instead of "deportation." But morally-speaking, "deportation" is condemned explicitly by the Second Vatican Council in its pastoral constitution "Gaudium et Spes" as one of the many "infamies" that "poison human society" and are "supreme dishonor to the Creator." The council's list of condemned includes "whatever is opposed to life," such as abortion, "whatever violates the integrity of the human person," such as torture, and "whatever insults human dignity," such as deportation. St. John Paul II reinforced the council's teaching in his 1993 encyclical "Veritatis Splendor," saying these acts are "intrinsically evil" and incompatible with the church's moral tradition "because they radically contradict the good of the person made in his (God's) image."In the days leading up to his selection as the vice presidential nominee, Vance also moderated his position on abortion. During his U.S. Senate bid, Vance said he supported a 15-week federal restriction on abortion -- a ban potentially affecting nearly 6% of abortions in the U.S. But on July 7 with NBC's Meet the Press, Vance instead aligned with Trump's view that abortion policy should be left to the states, and said he supported access to mifepristone, a pill commonly used for first-trimester abortion. Although mifepristone can be used in early miscarriage care protocols, Vance did not qualify his statement. Nearly nine out of 10 abortions take place within the first trimester, with the majority being performed through mifepristone.

But in a statement, Marjorie Dannenfelser, president of Susan B. Anthony Pro-Life America, called Vance "an exceptional selection as President Trump's running mate."

"His courage in exposing the Democrats' agenda of abortion for any reason, even in the seventh, eighth, or ninth month, helped propel him to a decisive victory in the 2022 midterm elections," Dannenfelser, whose group works to elect pro-life candidates to public office, said. "Vance's hardscrabble upbringing informs his compassionate approach to this issue. He saw firsthand how the deck can be stacked against women facing unexpected pregnancies if they do not have the support and resources they need, even though most would rather choose life. His ability to compellingly share these stories on a national stage will surely be an asset."

Dannenfelser said Vance's time in the Senate earned an "A+" on the organization's legislative scorecard.

"Now through Election Day, the pro-life movement's mission must be to defeat the Biden-Harris extreme abortion agenda," Dannenfelser argued. "With Vance on the ticket, we are more committed than ever in our efforts to deliver the winning pro-life message to 10 million voters, with four million visits to the homes of voters in key battleground states."

In a post on X, formerly Twitter, President Joe Biden wrote, "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."

In a statement, Biden-Harris 2024 Chair Jen O'Malley Dillon said Trump picked 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."

Former Vice President Mike Pence was Trump's running mate in the 2016 and 2020 elections but broke with Trump by rejecting Trump's unfounded claims of a stolen election and certifying Joe Biden's victory in the 2020 election despite the Jan. 6, 2021, riot at the U.S. Capitol. Pence has thus far declined to endorse his former running mate, but after the shooting at Trump's rally in Butler, Pennsylvania -- which is under investigation as an attempted assassination -- Pence said he was praying for Trump.

O'Malley Dillon added, "Over the next three and a half months, we will spend every single day making the case between the two starkly contrasting visions Americans will choose between at the ballot box this November: the Biden-Harris ticket who's focused on uniting the country, creating opportunity for everyone, and lowering costs; or Trump-Vance -- whose harmful agenda will take away Americans' rights, hurt the middle class, and make life more expensive -- all while benefiting the ultra-rich and greedy corporations."

Some have expressed interest in Vance's policy positions on issues including his support for a proposal by pro-life activists to make childbirth free for mothers and advancing other policies to support families.

"Vance is clearly interested in making marriage and family formation more affordable for ordinary Americans," Brad Wilcox, senior fellow at Institute for Family Studies, told OSV News.

"He's also got a markedly more energetic view of the role of public policy than did former Vice President Mike Pence," Wilcox said. Based on Vance's views, he said a Trump-Vance administration could potentially "advance a range of policy measures related to the marriage penalty, the child tax credit, and the costs of bearing and rearing children in America today."

If elected, Vance would be just the second Catholic vice president in U.S. history, preceded only by Biden, who was vice president for two terms before his own election to the White House.