Ted Cruz’s campaign spent more than $150,000 at US book chain Books-A-Million in the months after the Texas senator’s book was published, Forbes has reported.

Cruz, who was prominent among the Republicans trying to block the certification of Joe Biden’s election, published One Vote Away: How a Single Supreme Court Seat Can Change History in September. A financial disclosure he filed on Monday, reported on by Forbes, shows he received almost $320,000 as an advance in 2020 from the book’s publisher Regnery Publishing.

“With a simple majority on the Supreme Court, the left will have the power to curtail or even abolish the freedoms that have made our country a beacon to the world. We are one vote away from losing the Republic that the Founders handed down to us. Our most precious constitutional rights hang by a thread,” says Regnery of the title. “In One Vote Away, you will discover how often the high court decisions that affect your life have been decided by just one vote.”

The end-of-year report from Cruz’s committee, filed with the Federal Election Commission, reveals that two weeks after One Vote Away was published, his campaign spent $40,000 at Books-A-Million. Shortly afterwards, it spent a further $1,500, and in December, another $111,900. All of the purchases are described by the campaign as “books”, and Forbes speculated that they may have been used to boost his book sales, quoting Brett Kappel, a lawyer specialising in campaign finance, who said that “the FEC has issued a long series of advisory opinions allowing members to use campaign funds to buy copies of their own books at a discount from the publisher, provided that the royalties they would normally receive on those sales are given to charity”.

Forbes previously reported what three other US senators had made from book deals in 2020: Elizabeth Warren earned $278,000, Tom Cotton $202,000, and Tammy Duckworth $382,000. All three used campaign funds to buy books, but Forbes said that their purchases were all under $20,000.

A spokesperson for Cruz’s campaign told the magazine that the senator “has not received one cent of royalties in connection with any One Vote Away book sales”, but declined to reveal which books the campaign had spent more than $150,000 on.

When Donald Trump Jr published Triggered in 2019, it made the New York Times bestseller list, but the newspaper’s charts included a dagger beside the book to indicate that “some retailers report receiving bulk orders”. The Republican National Committee denied making bulk orders at the time, and Trump Jr was angered by the suggestion that his sales had been artificially boosted, retweeting Republican strategist Andrew Surabian’s claim that “Don did multiple book signings where he sold 1,000+ books apiece. BookScan data will show he sold more books than the #2 and #3 books combined. Media/Dems want to pretend otherwise, but he was #1 on merit.”