The U.S. Constitution is now the second-best selling book on Amazon.

For just a dollar, the pocket paperback version is bested only by "Harry Potter and the Cursed Child," which was released over the weekend.

"It felt great ... when I saw that it was right there with Harry Potter,"said Dan Sheridan, spokesman for National Center for Constitutional Studies, which publishes the edition.

The Constitution's ranking coincides with the buzz around Khizr Khan, the father of a fallen Muslim U.S. solider, who spoke at the Democratic National Convention last week. During his speech Thursday, Khan pulled out a copy of the Constitution to criticize Donald Trump.

"Donald Trump, you're asking Americans to trust you with their future. Let me ask you, have you even read the United States Constitution?" he asked, holding it up in the air. "I will gladly lend you my copy."

Sheridan said he sold 45,000 copies between Saturday morning and Monday evening. That number might be typical over a week, but not in three days, he added.

Amazon (AMZN) wouldn't offer any details on how the bestseller rankings have changed recently -- or when the Constitution hit No. 2 -- but the list is updated hourly based on sales. As of Tuesday afternoon, the price had gone up by 50 cents.

"That was [Amazon]," said Sheridan. "I'm assuming they raise the price just to capitalize on the movement of the copies... that [50 cents] goes to them."

Applewood Books, which publishes a $9.45 hardcover version of the Constitution, says its sales have spiked three times since the convention ended.

Demand for that edition has caused Amazon to list it as being temporarily out of stock. But Applewood Books founder and president Phil Zuckerman assured CNNMoney that they do have a larger supply.

"We do have it in stock," said Zuckerman. "Their messaging isn't always correct."

Related: Commission defends debate schedule amid Trump complaints

Although Zuckerman has seen demand spike this week, he says the Constitution has always been a "source of continuous sales" for him.

"It's not like people haven't been paying attention to it," the 40-year publishing veteran said. "Sales increase every year... and this year is no exception."

By the end of the day Monday, another version of the U.S. Constitution, on sale for $4.64, hit the No. 10 list as well.

The Constitution wasn't the only political book on Amazon's bestseller list. Also in the top 20 are "Armageddon: How Trump Can Beat Hillary," by Eileen McGann and "Hillary's America: The Secret History of the Democratic Party," by Dinesh D'Souza.

Related: Trump prevails over Clinton in convention speech ratings race

Clips of Khan's speech and images of him holding up the Constitution have gone viral since last Thursday.

Trump harshly criticized Khan over the weekend, which has prompted a backlash from his own party.

"While I feel deeply for the loss of his son, Mr. Khan who has never met me, has no right to stand in front of millions of people and claim I have never read the Constitution, (which is false) and say many other inaccurate things," Trump said in a statement.

Khan has since appeared on CNN's "State of the Union" and "New Day" to blast Trump for being "unfit for the leadership of this country" and possessing "ignorance and arrogance."