The American people have a right to know.

After House Intelligence Committee Chairman Devin Nunes, R-Calif., sent his memo laying out potential abuses of the FISA process by the FBI to the White House, Rep. Nancy Pelosi, D-Calif., demanded that he be removed as chairman. Nunes was "deliberately dishonest" in pushing to release a "bogus memo," Pelosi declared, and had "disgraced the House Intelligence Committee" with his "partisan effort to distort intelligence."

But Democrats can't so easily dismiss the far more detailed declassified criminal referral written by two respected Republican senators — Charles E. Grassley, R-Iowa, and Lindsey O. Graham, R-S.C. — which confirms the claims raised in the Nunes memo. The Grassley-Graham memo has been all but ignored since its release, but it deserves attention from everyone — and answers from the Justice Department.

If you're concerned about Russia meddling in our election, as every American should be, then you should be deeply concerned about unverified allegations by Russian government officials, passed on to the FBI by a paid partisan of one candidate, leading to a warrant to spy on an American citizen associated with the other campaign.

According to Grassley and Graham, that is precisely what happened. The FBI "relied heavily" on the Steele dossier to obtain warrants for surveillance of Carter Page, a marginal former Trump campaign adviser, the senators write. Moreover, they say, the FBI did not have "meaningful corroboration" of Steele's claims when it submitted its application to the Foreign Intelligence Surveillance Act court.

In other words, Steele's work was virtually the sole source of information the FBI relied upon to obtain a warrant to spy on a U.S. citizen. Without it, there would likely have been no surveillance approved.

The senators further confirm that the FBI did not, in fact, tell the court the full provenance of the dossier. They also failed to tell the court that an FBI official, Bruce Ohr (whose wife worked for Fusion GPS on the Russia project), had warned the bureau that "Steele was 'desperate' to see that Mr. Trump was not elected" even though this information was relevant "to his credibility and his stated political motive."

The senators note the FBI used the dossier because Steele was "considered reliable due to his past work with the Bureau." But in October 2016, the FBI suspended its relationship with Steele after it learned he had disclosed dossier information to the press and after he lied to the FBI about it. Yet despite Steele's deception, which calls into question his credibility, the FBI continued to rely on the dossier for renewals of the FISA warrant. Worse, the senators write, "the FBI did not subsequently disclose to the [court] this evidence suggesting that Mr. Steele had lied to the FBI."

None of these ugly details exonerate Trump or undercut the Mueller investigation. Nor was that the purpose. Both Graham and Grassley have always supported special counsel Robert S. Mueller III.

But if the FBI, wittingly or unwittingly, made representations before the court that were in error, then the American people have a right to know. And if a paid advocate of one presidential candidate persuaded the FBI to conduct surveillance on a member of the other candidate's campaign team, Congress has an obligation to investigate.

Thiessen is a Washington Post columnist. Follow him on Twitter, @marcthiessen.