When it comes to the opening by the Department of Justice of a criminal probe into Governor Cuomo the feds would do better, in our view, to fuhgeddaboudit. Washington is harrying the New York City mayoral frontrunner in next month’s Democratic primary over lies he allegedly told to Congress about his stewardship of the state during Covid-19. While lying to lawmakers is no minor matter, how could voters see a potential prosecution as anything but political?

Federal prosecution of Empire State politicos has long struck us as such. Witness the travails of one of Mr. Cuomo’s rivals, Mayor Adams. At the end of the Biden administration the justice department charged the mayor with bribery. After President Trump won back the presidency, Main Justice decided to dismiss the case. A rash of resignations ensued, along with an accusation of a “quid pro quo” between the White House and Hizzoner.

The government’s rationale for pushing for dismissal — which was eventually granted, “with prejudice,” meaning that charges can’t be refiled — was that the case “unduly restricted Mayor Adams’ ability to devote full attention and resources to illegal immigration and violent crime.” What is the logic, then, of ending the case against Mr. Adams and beginning one against Mr. Cuomo, who could soon succeed Mr. Adams as mayor? 

If Mr. Trump intends to use the DOJ to tip the scales toward Mr. Adams — the two appear in sync — the effect could be the opposite. The 47th president knows this first hand. The case brought against him by District Attorney Alvin Bragg appears to have bolstered his fortunes in the Republican presidential campaign. Special Counsel Jack Smith’s cases did Mr. Trump no political harm. Americans reckoned the prosecutions to be in the main political.

New York Democrats are piping up in Mr. Cuomo’s defense. “No one trusts the Trump Justice Department,” one of his rivals for mayor, Comptroller Brad Lander, says. “I don’t believe that Mr. Cuomo will be compromised if the Department of Justice is improperly weaponizing its power for political purposes,” Congressman Daniel Goldman of Brooklyn, who decries the prosecution as a matter of “legitimizing and crediting the misuse of official power,” avers.

The precedents of federal prosecutions of New York officials are on the whole baleful. Speaker Sheldon Silver was convicted of corruption. That verdict was overturned on appeal. He was convicted again, only to see the United States Appeals Circuit dismiss guilty verdicts on three of the charges and upheld them on others. Another lawmaker in Albany, Senator Joseph Bruno, was convicted on corruption charges that were overturned on appeal. 

During the prosecution of Silver we wrote that even were he “brought to justice, what would it say that it had to be done by the Federal government, rather than New York state’s own institutions?” To ask that question is hardly to defend his behavior — or that of Messrs. Cuomo and Adams. Attorney General Letitia James, who secured in state court a civil fraud verdict against Mr. Trump, is also being investigated by the DOJ.

All of this meddling in New York could set back Mr. Trump’s agenda in what was once his home state. It could empower Mr. Cuomo’s strongest challenger, Assemblyman Zohran Mamdani, a leftist. By what logic does the failure of lawfare by the Democrats recommend lawfare practiced by the GOP? Mr. Trump said during the campaign that “success” would be his retribution. If only New York’s Democrats adopted that standard.