Is it just us, or are the only people refusing to testify during Washington's ever-decreasing circle of Russiagate witch-hunting, the leftists who cast the largest aspersions in the first place?

Two of the co-founders of Fusion GPS, the opposition research firm behind the infamous Trump dossier, invoked their Fifth Amendment rights during a meeting with the House Intelligence Committee on Wednesday, a person familiar with the matter told The Daily Caller.

As a reminder, Fusion was working for an ally of Hillary Clinton’s last June when the firm hired Steele to investigate Donald Trump’s personal and business activities in Russia. The result is a 35-page document full of salacious and uncorroborated allegations about Trump and his campaign associates. The dossier has been cited by the FBI as part of its investigation into possible collusion between the Trump campaign and Russian operatives.

Congressional Republicans have questioned the FBI’s decision to rely on the dossier given that its most sensational allegations have not been proved. They are also interested in who hired Fusion.

And now, during a meeting with the House Intelligence Committee on Wednesday, Thomas Catan (left) and Peter Fritsch (right), the two Fusion GPS partners, reportedly plead the Fifth “to every question asked of them,” the source says.

As The Daily Caller notes, the House panel earlier this month subpoenaed Fritsch, Catan and their fellow partner, Glenn Simpson, to discuss their involvement in the dossier, which was compiled last year by former British spy Christopher Steele.

In a letter to California Rep. Devin Nunes earlier this week, Fusion’s attorneys suggested that the three partners, all former Wall Street Journal reporters, would refuse to cooperate with the committee, citing First Amendment protections and confidentiality agreements.

It was unclear from that letter whether the Fusion partners planned to plead the Fifth, which protects witnesses from self-incrimination.

And now we know.. one wonders what they have to hide?

We look forward to hearing from House Select Committee on Intelligence Chairman Rep. Devin Nunes (R-CA) and Ranking Member Rep. Adam Schiff (D-CA) on their thoughts about who in their investigation is forthcoming... and who is not.