The co-founder of the firm tied to the controversial opposition research dossier on President Trump has agreed to speak to the Senate Judiciary Committee behind closed doors, the top lawmakers on the panel said Tuesday.

In exchange for the interview, the committee will drop its subpoena of Glenn Simpson, co-founder of the Washington-based strategy firm Fusion GPS.

The subpoena was issued last week after Simpson declined the committee's request to appear before lawmakers in a public hearing.

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"However, since that time, Mr. Simpson, through his attorney, has agreed to provide a transcribed interview and requested that the subpoena compelling his attendance at Wednesday’s hearing be waived," committee Chairman Chuck Grassley Charles (Chuck) Ernest GrassleyGardner signals support for taking up Supreme Court nominee this year Grassley, Ernst pledge to 'evaluate' Trump's Supreme Court nominee McConnell digs in on vow to fill Ginsburg's Supreme Court seat MORE (R-Iowa) and Ranking Member Dianne Feinstein Dianne Emiel FeinsteinBiden leads Trump by 12 points among Catholic voters: poll Names to watch as Trump picks Ginsburg replacement on Supreme Court McConnell says Trump nominee to replace Ginsburg will get Senate vote MORE (D-Calif.) said in a statement.

"We’ve reached an agreement on this request and have withdrawn the subpoena," they added.

Fusion GPS came to the committee's attention after a dossier it had commissioned from a former British spy during the campaign was published. The dossier contains salacious allegations about Trump that haven't been verified.

The Judiciary Committee, as well as several other panels, are conducting investigations into Russia's role in the 2016 election, as well as possible collusion between the Trump campaign and Moscow.

The Judiciary Committee issued a subpoena late Monday compelling Trump's former campaign manager Paul Manafort to appear before the committee on Wednesday.

Manafort met with congressional investigators on the Senate Intelligence Committee on Tuesday to discuss a June 2016 meeting between Trump campaign members and a Russian lawyer, who had promised dirt on then-Democratic candidate Hillary Clinton Hillary Diane Rodham ClintonJoe Biden looks to expand election battleground into Trump country Biden leads Trump by 12 points among Catholic voters: poll The Hill's Campaign Report: Biden goes on offense MORE. In emails setting up the meeting, the information was described as part of a Russian government effort to elect Trump.

That hearing was held behind closed doors.

The Judiciary Committee's meeting on Wednesday will focus primarily on the Foreign Agents Registration Act, which requires those who lobby on behalf of foreign interests to register with the Justice Department.