We have as close to a national consensus as possible in the war against ISIS.

Polls show the public wants strong measures. Practically everyone on the political spectrum says the terror group should be destroyed, even Elizabeth Warren and Rand Paul. President Barack Obama has given a prime-time speech committing the country to a yearslong war.

And yet Congress can’t bring itself to vote to authorize military action. President Obama doesn’t want to ask for an authorization, and Congress doesn’t want to be asked. Who says that no one can get along in Washington? When it comes to evading democratic accountability, the consensus is broad and deep.

The advantages of an authorization are obvious. It would be an unmistakable statement of national will. It would communicate to our allies our seriousness. It would put everyone on record, so if the war goes badly it is harder for finger-in-the-wind members of Congress to bail out.

Even more obvious is the alliance of convenience between President Obama and Congress to avoid a vote (except on the more limited mission of arming and training Syrian rebels). The president doesn’t want to be bothered, especially after his ill-fated quest for a vote to authorize bombing Syria last year (the effort seemed doomed before he pulled the plug). And Congress doesn’t want to bother, not with an election looming and not when a vote would require taking needless responsibility.

So the president rummages around his desk drawers searching for a legal basis for his war, while Congress mumbles and looks at its shoes. Such are the exertions of the nation’s political branches as they embark on a long fight against an enemy of the United States.

Even if it is unauthorized, the war against ISIS is not illegal. The president has the inherent authority as commander in chief to act against a threat to the United States, and Americans have been killed by ISIS.

But Harvard Law School professor Jack Goldsmith points out the problem for the administration in asserting this view. Under the War Powers Resolution — a fetish of the left — Congress must authorize military action 60 days after it is undertaken. So, unless the administration wants to openly defy the resolution — as it did during the Libya War when it argued that the monthslong bombing campaign against Moammar Gadhafi didn’t constitute “hostilities” — it would still need congressional authorization.

It prefers, then, to argue that the war has already been authorized. It is relying primarily on the 2001 authorization against those who “planned, authorized, committed, or aided” the Sept. 11 attacks, or “harbored” those who did. This has been taken as a broad mandate to hit al-Qaida or al-Qaida-allied groups.

Its application to ISIS is dubious, though. ISIS didn’t commit 9/11, and it is fighting al-Qaida rather than being allied with it.

As backup, the administration says the 2002 authorization for the Iraq War still applies. This, too, is tenuous. The 2002 legislation authorized the president “to defend the national security of the United States against the continuing threat posed by Iraq.” The regime that constituted that threat is long gone, and President Obama declared the war over years ago.

It wasn’t long ago that President Obama was a scold about how important it was for Congress to authorize military interventions. It wasn’t long ago that his administration considered the 2001 and 2002 authorizations dated and overly broad, and talked of their repeal. Now, he is happy to sidestep Congress by any legalistic parsing necessary.

Just because the president doesn’t want to push for an authorization doesn’t mean Congress has to stand by the sidelines. Yet that is where it is happy to be. The fight against ISIS will be accompanied by fiery denunciations of the group’s barbarism and ringing statements of resolve. It will include everything, it seems, but a congressional vote of authorization. How pathetic.

Rich Lowry can be reached via e-mail: comments.lowry@nationalreview.com.