The mystery over whether Donald Trump Jr’s new book deserved its place at No 1 in the New York Times bestseller list has deepened after it emerged that the Republican National Committee (RNC) spent $94,800 (£74,000) on a bulk order of the book a week before it was released.

Triggered, billed as the book the “left doesn’t want you to read”, was published on 5 November and heavily promoted by the RNC, which emailed supporters offering signed copies for sale. It went on to top the prestigious hardcover non-fiction list.

According to reports in the New York Times, a financial disclosure form filed to the Federal Election Commission showed a 29 October payment for $94,800 to the bookseller Books-A-Million. The RNC spokesperson Mike Reed confirmed the payment had been for copies of Triggered, having previously said: “We haven’t made a large bulk purchase, but are ordering copies to keep up with demand. Each book is sold to an individual who supports the Republican party.”

The book is believed to have sold more than 115,000 copies, according to NPD BookScan, which tracks physical print sales in the US. The RNC said $500,000 had been raised from sales of the book. When it debuted in the bestseller list, Trump Jr tweeted: “Thanks Deplorables! You’re the best.”

This is not the first time claims have been made about sales of Trump Jr’s book being inflated. The New York Times bestseller list marks books with a dagger if retailers report there have been bulk sales, which it did for Triggered. When it topped the chart, it was the only book in the top 10 list to feature the dagger.

The Hachette imprint Center Street, which published the book, has previously said that it did not “have knowledge of third-party book purchases”. The book’s launch was marred when Trump Jr was heckled at one of his own events for refusing to take part in a Q&A session.