The House Intelligence Committee on Thursday morning voted unanimously to release the transcript of its seven-hour interview with Glenn Simpson, the co-founder of the opposition research firm that helped assemble the controversial "Steele dossier," a source familiar with the vote told The Hill.

The vote comes on the heels of the unilateral release of the Senate Judiciary Committee's interview with Simpson by ranking member Dianne Feinstein Dianne Emiel FeinsteinMcConnell says Trump nominee to replace Ginsburg will get Senate vote Top Democrats call for DOJ watchdog to probe Barr over possible 2020 election influence Intensifying natural disasters do little to move needle on climate efforts MORE (D-Calif.). House Intel Democrats have since been pushing for the release of the transcript of their interview, which took place behind closed doors in November.

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President Trump Donald John TrumpUS reimposes UN sanctions on Iran amid increasing tensions Jeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Trump supporters chant 'Fill that seat' at North Carolina rally MORE slammed the release of the Judiciary transcript as "underhanded" and "possibly illegal," a claim that legal experts and lawyers dismissed as untrue.

Simpson's firm, Fusion GPS, has become a flashpoint in the national controversy over the dossier, a set of memos compiled by former British intelligence officer Christopher Steele and paid for in part by the Democratic National Committee and Hillary Clinton Hillary Diane Rodham ClintonJeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Momentum growing among Republicans for Supreme Court vote before Election Day Warning signs flash for Lindsey Graham in South Carolina MORE’s presidential campaign that contained unverified allegations against Trump and his ties to Russia.

The source indicated the transcripts would post on the House Intelligence Committee website later Thursday.

The president’s allies argued that Simpson’s Judiciary testimony did nothing to undercut their core claim that the FBI had used the dossier to investigate Trump and possibly to secure a FISA warrant to spy on Trump officials during the campaign and transition.

Democrats responded by declaring that Simpson’s testimony bolstered allegations in the dossier and Steele's credibility.

Olivia Beavers contributed.

Updated at 11:13 a.m.