Matthew Continetti analyzes former President Donald Trump’s choice of J.D. Vance as his running mate.

Donald Trump’s contempt for the Washington establishment is well known. He challenges, confronts and subverts its institutions, its media, its consultants, its euphemisms and its unwritten codes of conduct. Choosing Senator J.D. Vance of Ohio to be his running mate is the latest example of the former president’s willingness to flout political convention.

Previous vice-presidential nominees were selected to forge party unity, capture a crucial swing state or help an outsider president navigate Washington. Mr. Vance doesn’t fit these criteria. But then Mr. Trump has never been a traditional candidate. And he probably had more on his mind than 2024 when he put Mr. Vance on the ticket. He was probably thinking of 2028 and beyond — and where he wants the G.O.P. to go. …

… Mr. Trump appears to value Mr. Vance’s evolution from opponent to stalwart. Mr. Vance has the zeal of a convert to Mr. Trump and to Trumpism and is unlikely to use the vice-presidential residence as a base of operations for pro-immigration, interventionist Republicans. He defends Mr. Trump’s conduct after the 2020 election and has adopted Mr. Trump’s enemies as his own.

Mr. Vance’s biography must have also appealed to Mr. Trump. Mr. Vance grew up in poverty, joined the Marines after the Sept. 11, 2001, terrorist attacks, wrote a best-selling autobiography and succeeded in business. His working-class roots may appeal to the forgotten men and women of the Rust Belt who are at the heart of Mr. Trump’s campaign.

Another potential asset is Mr. Vance’s age. Republicans are doing comparatively well with young male voters this year, and Mr. Vance may help the party capitalize on this growing advantage. There is a long tail to the Vance nomination. Richard Nixon was also 39 years old when Dwight Eisenhower chose him as a running mate in 1952. Mr. Nixon played a central role in American politics for 22 years.

Mr. Trump so totally dominates today’s Republican Party that he feels no need to build bridges within it.