President Obama is signaling his plans for an extensive effort aimed at getting Merrick Garland confirmed to the Supreme Court. A front-page New York Times article lays out what it describes as “a deliberate White House strategy,” consisting of three phases, including “speeches, interviews and other public events” by Mr. Obama, and “targeted advertising” by supportive outside groups. It will be an “all-out public relations campaign aimed at demanding a final, up-or-down vote.”

Where, one wonders, is the equivalent and parallel effort from the president and his administration aimed at winning an authorization from Congress to use military force against the Islamic State? One might think — or at least hope — that it would be a priority for the administration.

On March 17, Secretary of State Kerry announced that the Islamic State — which he refers to by the pejorative Arabic acronym Daesh — “is responsible for genocide against groups in areas under its control, including Yezidis, Christians, and Shia Muslims.” Said Mr. Kerry: “The fact is that Daesh kills Christians because they are Christians; Yezidis because they are Yezidis; Shia because they are Shia.”

The Secretary said, “We know, for example, that in August of 2014 Daesh killed hundreds of Yezidi men and older women in the town of Kocho and trapped tens of thousands of Yezidis on Mount Sinjar without allowing access to food, water, or medical care….We know that in Mosul, Qaraqosh, and elsewhere, Daesh has executed Christians solely because of their faith; that it executed 49 Coptic and Ethiopian Christians in Libya; and that it has also forced Christian women and girls into sexual slavery.”

Nor are the Islamic State’s offenses confined to the Middle East. As if genocide weren’t bad enough, the group and its sympathizers have also been launching terrorist attacks that killed 32 people at the airport and a subway station in Brussels last month, 130 people in Paris in November, and 14 people at San Bernardino, Calif., in December.

If genocidal terrorists targeting Western capitals and the American mainland don’t merit a declaration of war, or at least a Congressional authorization to use force, it’s hard to imagine what would, short of another Pearl Harbor or September 11 attack.

Congressional action has broad support across partisan boundaries and the ideological spectrum. An authorization is backed in principle — though there are differences over the wording — both by the editor of the libertarian Reason, Nick Gillespie, and by the more interventionist editors of the Wall Street Journal editorial page.

President Obama, in a December 6, 2015, Oval Office speech following the San Bernardino shooting, said, “if Congress believes, as I do, that we are at war with ISIL, it should go ahead and vote to authorize the continued use of military force against these terrorists. For over a year, I have ordered our military to take thousands of airstrikes against ISIL targets. I think it’s time for Congress to vote to demonstrate that the American people are united, and committed, to this fight.”

Resolutions to authorize force against the Islamic State have been introduced in the Senate by Republicans Mitch McConnell, Lindsey Graham, Orrin Hatch, Joni Ernst, and Marco Rubio, and in the House by a senior Republican lawmaker, Tom Cole. In November, a group of 35 members of Congress, including Mr. Cole, Justin Amash, John Conyers, John Lewis, and Charles Rangel, wrote a letter to the speaker of the House, Paul Ryan, asking him to schedule a debate and vote on an Authorization for the Use of Military Force — or “AUMF,” in Beltway lingo — “as quickly as possible.”

Some argue that President Obama already has all the warmaking authority he needs, under either his Constitutional Article II power as commander in chief or the post-September 11 authorization of the use of force against “against those nations, organizations, or persons he determines planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harbored such organizations or persons.” The administration has deployed 5,000 troops to Iraq and used drones and air strikes across the Mideast even without additional overt authorization from Congress.

With a genocide and a terrorist onslaught under way, congressional inaction sends a signal of irresolution and indifference. President Obama’s own reluctance to launch a Supreme Court-nomination-style political offensive on the topic is typical of his own “reticence about intervention” — as Jeffrey Goldberg puts it — and also a sign of his belief that, as he told Mr. Goldberg for an article in the Atlantic, “ISIS is not an existential threat to the United States.”

Readers may want to ask their own senators and congressmen, even presidential candidates, about this. It could be phrased like this: Do you support President Obama’s request, and Senate Majority Leader McConnell’s resolution, for authorizing the use of military force against the Islamic State? And if not, precisely what number of additional deaths, in what combination of genocide and terrorist attacks, would it take for you to support such an authorization?

Mr. Stoll is editor of FutureOfCapitalism.com.