HALF A year after the beginning of the war against the Islamic State, Congress has not yet voted to authorize it — a shameful state of affairs for which the White House and legislative leaders blame each other. They are both right: Mr. Obama said he wanted a congressional vote, but he did not release a proposed authorization for the use of military force (AUMF) until last week . Congress, meanwhile, stalled its own legislation, as leaders who regularly accuse Mr. Obama of abuse of power made clear that they did not wish to take responsibility for the new war in Iraq and Syria.

Unfortunately, the draft legislation that Mr. Obama finally unveiled Wednesday does not provide a quick path to congressional action. It is an unwieldy legal and political amalgam that expands presidential authority in ways that alarm even some hawkish conservatives, while also seeking to limit the options of the next president in combating the Islamic State.

Mr. Obama’s draft authorizes war against the Islamic State for only three years and rules out “enduring offensive ground combat operations,” language that quickly drew objections from Republican hawks for its limitations. But experts, like conservative Harvard professor Jack Goldsmith, were quick to point out that in other ways Mr. Obama’s proposal would grant a sweeping expansion of presidential authority. His bill permits action anywhere in the world and against not just the Islamic State but “associated forces,” which are so broadly defined that they could include secular groups fighting the Assad regime in Syria, militants in Libya or Nigeria, or even the lone terrorist who attacked a kosher supermarket in Paris.

The 2001 AUMF against al-Qaeda, which Mr. Obama has cited as authorization for the war thus far, has a stricter definition of “associated forces” that can be targeted. But it does not limit the use of ground forces. Since Mr. Obama’s draft does not repeal the 2001 legislation, he and the next president would be able to use the broad authorization of the new bill to target a wide variety of groups and individuals while relying on the first AUMF to deploy ground forces and ignore the three-year time limit.

To be sure, Mr. Obama’s limiting language, including his restrictions on ground troops, would serve as a political check. But as Harvard professor Noah Feldman observed, no one expects this president to launch a large offensive ground operation in the Middle East in any case. At the same time, his language would constrain the next president, at least during the first year of his or her term. Neither Mr. Obama nor Congress should seek to limit military decisions that might be taken by the next commander in chief, even if the restrictions were not legally binding.

What’s most important is that Congress vote to authorize the war now underway. Recognizing that — and the political reality that both houses are controlled by the GOP — the president and Democrats should settle for a short and simple authorization to fight the Islamic State, without seeking either to expand the president’s existing statutory authority or limit his use of forces. That should be a middle way that a majority can accept.