Author and journalist Matt Taibbi fielded scathing questions by House Democrats on Thursday as he sought to defend his contributions to the so-called “Twitter Files” during a hearing for the House Subcommittee on the Weaponization of the Federal Government.

The hearing became tense at times, with the top Democrat on the panel, Del. Stacey Plaskett (U.S. Virgin Islands), repeatedly pushing back against the top Republican, Rep. Jim Jordan (R-Ohio). Jordan and others in his party allege federal agencies have been unfairly targeting conservatives.

In an attempt to prove that point, new Twitter CEO Elon Musk allowed a swath of internal company documents to be leaked late last year to a conservative-leaning group of journalists and commentators. The resulting articles supposedly proved that, under its previous leadership, Twitter had pushed a progressive agenda onto users and worked with federal agencies to silence conservative voices on the site. But critics say it came up short, merely serving to illustrate how difficult it is to moderate content on a large social media platform.

Taibbi testified that the Twitter story was “by far the most serious thing” and “the most brave story” he had ever worked on, surpassing even the financial crisis of 2008.