Conflicting reports emerged Thursday about whether the co-founder of the opposition research firm behind the infamous "dossier" allegedly detailing President Trump's ties to Russia would testify before the Senate Intelligence Committee next week.

Glenn Simpson, a former Wall Street Journal reporter who helped found Fusion GPS in 2010, was asked to appear at a scheduled July 19 hearing about the role of foreign lobbying in last year's presidential election.

However, Politico, citing two sources, reported that Simpson did not plan to testify. The report added that it was not immediately clear whether the committee planned to compel Simpson to testify. By contrast, The Washington Times reported Thursday that Simpson would testify before the panel.

During the campaign, Fusion GPS contracted former MI-6 agent Christopher Steele to build a report on Trump's financial and social connections in Russia. The dossier included a number of sordid allegations about Trump's sexual proclivities, which the president has repeatedly denied.

On Wednesday, Fox News reported that Fusion GPS had ties to Russian efforts to undermine U.S. sanctions that were led by attorney Natalia Veselnitskaya. Veselnitskaya was at the center of a political storm earlier this week after Donald Trump Jr. made public emails indicating that he had taken a meeting with Veselnitskaya on the promise of receiving damaging information about Hillary Clinton.

Investment manager Bill Browder has alleged that Simpson was retained by Veselnitskaya's client, Prevezon Holdings, as part of an effort to repeal the Magnitsky Act, named for Sergei Magnitsky — an attorney who was beaten to death in a Moscow prison after accusing Russian authorities of stealing hundreds of millions of dollars through tax refunds and then laundering the money through New York banks.

Browder, a former Magnitsky client, told Fox News that Simpson was "using all of his media contacts to get a smear campaign going against Magnitsky and myself. He also seems to be able to get articles stopped. Simpson has unusual influence because he was often a big source to these reporters on other stories.”

Browder has also claimed that "Veselnitskaya probably tried 12 different angles to get to Trump and also to Clinton for that matter" and said she had "every possible incentive to get to both sides” since her goal was to get the Magnitsky Act repealed, and apparently not to influence the U.S. election."

In a statement, Fusion said it had nothing to do with the Trump Jr. meeting.

“Fusion GPS learned about this meeting from news reports and had no prior knowledge of it. Any claim that Fusion GPS arranged or facilitated this meeting in any way is absolutely false,” the statement read.