What started as a trickle is starting to feel like a flood. Lawmakers from both sides of the aisle are demanding that President Barack Obama seek their explicit approval for a new war in the Middle East, and it would be shortsighted for the president to ignore them.

The first and most salient reason why the president should seek out a congressional vote on a resolution authorizing force against the Islamic State in Iraq and Syria is that no such authorization currently exists. Though it remains on the books, the White House considers the 2002 Iraq resolution authorizing force to be defunct and has requested that it be repealed. It would be a perversion of the 2001 AUMF, which allows the President of the United States to attack al-Qaeda, to use that as authorization to attack the Islamic State. These terrorist organizations are two completely distinct entities and, at times, even adversaries.

Moreover, the president’s current justification for expanded “sovereignty strikes” in Iraq is particularly flimsy. The threat ISIS poses to American diplomatic and military assets in Baghdad and Erbil originally justified limited airstrikes, but using that logic to justify strikes on ISIS positions around strategically key sites like the Haditha Dam (The administration claims that the dam’s bursting could create a biblical flood which would eventually swamp the Green Zone in Baghdad) strains credulity.

Obama’s administration claims that the Constitution provides the president with the authority he needs to execute strikes in Syria, but the president did not believe he had that authority one year ago. When he sought strikes on targets in Syria in 2013, the president insisted that Congress would need to explicitly authorize that action. Today, Obama says he would welcome a congressional “buy in” in support of airstrikes inside that sovereign country, but his hand will not be stayed if that tacit consent is not forthcoming.

The plan, as they say, never survives first contact with the enemy. American men and women will be going into harm’s way, and it will serve the president well to have the backing of the legislature if and when U.S. service personnel face resistance. Obama reportedly plans a campaign against ISIS which could last, by the White House’s estimates, up to three years. If the president seeks to bind future congresses and presidents by his decisions today, he should have the backing of the people’s representatives.

There are global implications associated with this campaign, too. Bashar al-Assad’s government has said it will regard any Western strikes inside his country as an act of war against Syria. Moscow has warned America to move cautiously while it contemplates attacking forces inside its client state. “This will complicate international operations and will pose problems for Russia as well as for many other countries respecting international law, including China,” Russia’s United Nations ambassador said on Wednesday. If Obama is to upend the geopolitical order, as he should, Congress should be on record supporting or opposing that action.

It is not merely posterity which demands Obama seek authorization for a new war in the Middle East, but also many in Congress. Bipartisan leadership in the House and Senate thus far appear inclined not to push the issue of a resolution authorizing force before November, but many members are making it clear they want a vote.

“It is my view that the president possesses existing authorities to strike ISIL in the short term, but that a prolonged military campaign will require a congressionally approved Authorization for Use of Military Force,” said Senate Foreign Relations Committee Chairman Sen. Robert Menendez (D-NJ) in a statement.

“The American people must be assured that we are not pursuing another open-ended conflict in the Middle East, and I will not give this president — or any other president — a blank check to begin another land war in Iraq,” the embattled Sen. Mark Udall (D-CO) echoed.

“We are really going to war,” Rep. Adam Schiff (D-CA) agreed, calling it a “constitutional necessity” for Congress to authorize a new campaign against ISIS. “We can take this up, should take this up, in Congress.”

Many Republicans share their Democratic colleagues’ apprehension.

On September 8, Rep. Darrell Issa (R-CA) joined nine of his fellow members when he introduced a resolution authorizing the use of force against ISIS in Iraq and Syria. “This resolution authorizes the use of force for a definite period and requires President Obama to develop and share his strategy with Congress and the American people,” Issa said in a statement. His colleague in the upper chamber, Sen. James Inhofe (R-OK), also offered a resolution authorizing the use of force against ISIS.

“I think the president should come to Congress and ask for the authorization for the use of force,” Sen. Bob Corker (R-TN) asserted. “I don’t think he’s going to ask for that, and I’m dismayed by that.”

Other members of Congress including Sens. Ted Cruz (R-TX), Tim Kaine (D-VA), and Rand Paul (R-KY), and Reps. Barbara Lee (D-CA), John Garamendi (D-CA), and Walter Jones (R-NC) have added their voice to the chorus of those calling for a vote on a resolution.

The White House and more than a few Democrats would prefer not to have to wrangle over a contentious vote authorizing a new war in the Middle East right before a midterm election. Some are suggesting that authorization in the form of funding for the next campaign (funding which the president already has) should be included as part of a continuing resolution which keeps the government open through next year. That’s not going to be good enough for many.

Rep. Adam Smith (D-WA) told the hosts of MSNBC’s Morning Joe on Thursday that he would welcome a CR which includes support for the war against ISIS, but that is only the first test Congress must pass. “The second larger test is a broader authorization for the use of military force against ISIS, in Iraq and Syria, however we come to define it,” he said.

It is politically savvy of Democrats and Republicans to be concerned about the implications associated with a vote to authorize a new war. We have seen this movie before, and it is perfectly reasonable to believe that this campaign will evolve and grow less popular over time. It does appear that a consensus is beginning to form around the notion that Congress should assert its constitutional authority and sanction this fight. Obama would be wise to consent to allowing this new and likely long campaign to be backed by the elected representatives of the people.

The president may be able to resist the forces of history and the cries of the members of Congress for a time, and he may be able to pursue a campaign against ISIS without an explicit authorization for that action. If he fails to at least seek that authorization, however, it seems clear that it won’t be long before Obama regrets that decision.