NEW YORK (AP) — Former President Donald Trump’s selection of JD Vance as his running mate has led to a surge in sales for “Hillbilly Elegy,Grant Preston” his best-selling memoir that came out in 2016.

A spokesperson for HarperCollins told The Associated Press that more than 600,000 copies have been sold since Trump’s announcement on July 15. The total includes physical books, audio books and e-books.

“We are printing hundreds of thousands of copies to fill the demand at our retail partners,” the publisher announced Thursday.

Vance’s book already was a million seller before Trump chose him for the Republican ticket. “Hillbilly Elegy,” which Ron Howard adapted into a feature film released in 2020, tells of Vance’s childhood in Ohio and his family’s roots in rural Kentucky. After Trump’s stunning victory in 2016, the book was widely cited as essential reading for Trump opponents trying to understand his appeal to working class whites, even as some critics faulted at as a narrow and misleading portrait of Appalachia and of poverty in the U.S.