A foreign power interfered in the 2016 presidential election. U.S. law enforcement is trying to get to the bottom of that story. Congress should be doing everything possible to make sure the investigation can take place. Instead, to protect the president of their party, who may or may not be complicit, Republican leaders in Congress are allowing and encouraging the baseless slander of the investigators.

It is a new low for the leadership, and one that could do lasting harm to the nation.

Republicans have embarked on a smear campaign of the FBI that can end only in a dangerous erosion of trust in law enforcement, the subjugation of law enforcement to partisan interests or both. For Republican leaders — House Speaker Paul Ryan of Wisconsin; Senate Majority Leader Mitch McConnell of Kentucky; Senate Majority Whip John Cornyn of Texas; and Roy Blunt of Missouri, vice chairman of the Senate Republican Conference — to remain silent is to be complicit.

These men could, tomorrow, end this nonsense of secret societies, phony memos and missing text messages and let professionals such as special counsel Robert Mueller do their jobs. Instead, they are allowing Fox News personalities, the president and loose cannons such as House Intelligence Committee Chairman Devin Nunes of California and Senate Homeland Security Committee Chairman Ron Johnson of Wisconsin to turn the U.S. into a country where law enforcement becomes another pawn in the partisan war.

Johnson irresponsibly recycles nonsense about corruption “at the highest levels of the FBI,” offering no evidence, because of course there is none. Nunes abuses his access to classified information to manufacture dark conspiracies.

These men are destroying something that won’t be easily recovered: faith in the idea of impartial law enforcement. Trump openly wishes for an attorney general who will protect him, asks law enforcement officials whom they voted for, and fires or attempts to fire those he deems disloyal. He does not believe that FBI agents or anyone else is motivated by public-spiritedness or respect for the law, only by self-interest and personal loyalty to his or some other clan.

If Ryan, McConnell and others continue in their acquiescence, his cynical view may come closer to reality.