The New York Times fired back at Joe Biden’s campaign Wednesday, defending its decision to run an op-ed by Peter Schweizer, a senior contributor at Breitbart News who also helms a non-profit think tank focused on government accountability.

The dust-up started when the Biden campaign sent a letter to the Times lambasting the outlet for running an opinion piece by Schweizer detailing the numerous instances in which the former vice president’s political influence seemed to intersect with the business dealings of his youngest son, Hunter. The letter, which was authored by deputy campaign manager Kate Bedingfield, accused the Times of not having “internalized the sobering lessons of 2016” by giving “top billing” to a “right-wing polemicist” like Schweizer.

“But today’s decision is hardly the first example,” Bedingfield wrote, before proceeding to claim the Times had an “outsized hand in the spread of a baseless conspiracy theory” concerning the Biden family. “What was especially troubling about the Times’s active participation in this smear campaign is that prior to its reporting… this conspiracy had been relegated to the likes of Breitbart, Russian propaganda, and another conspiracy theorist, regular Hannity guest John Solomon.”

The Times did not take kindly to the accusation, telling CNN in a statement that its prior “coverage of the Biden campaign and Hunter Biden has been fair and accurate.” The outlet further added it would “continue to cover Joe Biden with the same tough and fair standards we apply to every candidate in the race and we’re happy to sit down with Biden advisers anytime to discuss news coverage.”

On the topic of Schweizer, the Times defended its decision to publish his op-ed, noting that, far from being a “right-wing polemicist,” he had expertise in ethics and public corruption through his position as president of the Government Accountability Institute.

“The op-ed makes an argument that nonpartisan government watchdogs would make, arguing in favor of a law that would prohibit self-dealing by those with government connections,” a spokesperson for the paper said.

Biden’s attack on the Times comes as his son’s business dealings have spilled into the open amid the impeachment inquiry into President Donald Trump. Schweizer, who previously chronicled the troubling fundraising practices of the Clinton Foundation, has been at the forefront of the topic since the publication of his bestselling book — Secret Empires: How the American Political Class Hides Corruption and Enriches Family and Friends — in 2018. In particular, Schweizer has exposed how Hunter Biden profited off deals with Ukraine and China that appeared inaccessible to average American businessmen, at the same time his father was responsible for helping formulate the Obama administration’s policy towards both countries.