House Republicans released a witness list that includes Hunter Biden and the Ukraine whistleblower, demanding they testify publicly so Trump can "face his accusers."
"The decision to voluntarily discontinue these cases was a difficult one," Cohen's attorney said.
Interviews of witnesses are done and the committee should begin releasing the transcripts, Grassley said.
In a 165-page transcript of testimony, Simpson discusses Trump's shadowy business dealings.
In testimony released Tuesday, Glenn Simpson spoke about dossier author Christopher Steele.
Two GOP Senators recommended criminal charges against the dossier's author.
Top congressional leaders want Justice to investigate former British spy Christopher Steele.
Political research firm calls for Congress to release their testimony in Russia investigation.
Fusion GPS denies it paid money to journalists to spread reports about its dossier alleging Donald Trump's links to Russia.
But Trump's Monday tweets about Fusion GPS aren't quite accurate.
The Washington Free Beacon, a conservative website largely funded by Republican donor Paul Singer, was the first to hire firm Fusion GPS.
The Clinton campaign and DNC helped finance the Steele dossier, but important elements of the document have panned out.