House Speaker Paul D. Ryan (R-Wis.) meets with reporters during his weekly news conference on Capitol Hill on May 10. (J. Scott Applewhite/AP)

House Speaker Paul D. Ryan’s last year in office is proving disastrous, a fitting end to the speakership of a man once considered a principled conservative reformer. His refusal to fulfill his constitutional role as leader of the House but rather play the role of presidential poodle and Republican attack dog for his increasingly unhinged caucus has had dire consequences for the GOP House majority, the intelligence oversight process and the broader conservative movement.

Among his most egregious failures has been his refusal to rein in House Intelligence Committee Chairman Devin Nunes (R-Calif.), who, in concert with the White House, created a phony “unmasking” scandal and released a misleading memo casting aspersions on the FBI and the Foreign Intelligence Surveillance Court in connection with the warrant to conduct surveillance on suspected spy Carter Page. As Nunes’s crowd, together with the president, now threatens to reveal a secret FBI and CIA source, in an unprecedented breach of the House’s intelligence oversight responsibilities, the extent of Ryan’s reckless disregard for his oath becomes clear.

The Post reports on the role of a retired American professor who cooperated with U.S. intelligence in investigating highly questionable contacts between Russian and the Trump campaign:

The role played by the source is now at the center of a battle that has pitted President Trump against his own Justice Department and fueled the president’s attacks on the special counsel’s investigation. … There is no evidence to suggest someone was planted with the campaign. The source in question engaged in a months-long pattern of seeking out and meeting three different Trump campaign officials.

The Washington Post — after speaking with people familiar with his role — has confirmed the identity of the FBI source who assisted the investigation, but is not reporting his name following warnings from U.S. intelligence officials that exposing him could endanger him or his contacts.

There is no evidence the FBI behaved improperly. (“The FBI commonly uses sources and informants to gather evidence and its regulations allow for use of informants even before a formal investigation has been opened. In many law enforcement investigations, the use of sources and informants precedes more invasive techniques such as electronic surveillance.”)

Indeed, had the FBI failed to follow up on evidence that a presidential campaign was engaged in secret communications with a foreign government, it would have been excoriated for dereliction of duty. Moreover, none of this was revealed during the campaign — in stark contrast to the airing of the allegations against Hillary Clinton for misuse of email, an action that looks downright trivial in comparison with a far-flung Russian plot to boost Trump, a scheme that at critical points was eagerly greeted by top members of the Trump campaign. (Trump himself of course publicly encouraged the hacking of the Democratic National Committee and John Podesta’s emails and made hay out of them in the closing days of the campaign.)

At any stage in this outrageous attack on American intelligence operations and the Justice Department, Ryan could have stepped in to replace members of the Intelligence Committee, to reprimand them and/or to rebuff the president’s attempt to interfere with and smear investigators seeking to uncover an attack on our democracy. Should the source be revealed, endangering lives and/or national intelligence-gathering, the blame should fall at least in part on Ryan. (“The stakes are so high that the FBI has been working over the past two weeks to mitigate the potential damage if the source’s identity were revealed, according to several people familiar with the matter. The bureau took steps to protect other live investigations that he has worked on and sought to lessen any danger to associates if his identity became known, said these people, who spoke on the condition of anonymity to discuss sensitive intelligence operations.”)

Ryan’s legacy will be not only of someone who politically enabled an unfit president, but also of someone who presided over the erosion of trust required for a proper intelligence oversight process. Ryan has done his party no favors in permitting it to become irrational conspiratorialists and antagonists of our intelligence community. His passivity has only encouraged Trump to abuse his powers, which may, when the facts are laid bare, amount to obstruction of justice.

This week Ryan completely lost control of his own troops, watching the farm bill go down in humiliating fashion as he tried to stave off an immigration compromise that might actually pass. He is no longer doing the people’s business — either to pass necessary, bipartisan legislation or to defend the people’s security. Perhaps he should retire now. Any temporary replacement could hardly do a worse job for the remaining months of the GOP majority.